DSE Endo

PANCE Review · Endocrine

High-Yield Practice Exam

PANCE Endocrine System (7%) — clinical application vignettes

50 vignette-style questions  |  Choose the single best answer  |  Answer key and rationales begin after Question 50

Name: ______________________________     Date: ____________     Score: ______ / 50

1.  A 68-year-old man in the ICU on day 9 of treatment for septic shock has thyroid tests drawn. TSH 1.8 (normal), free T4 normal, free T3 low, reverse T3 elevated. He has no history of thyroid disease and no goiter. What is the most appropriate management?

A.  Start levothyroxine 100 mcg daily

B.  Start IV liothyronine

C.  Order a thyroid uptake scan

D.  No thyroid hormone treatment; recheck after recovery (euthyroid sick syndrome)

E.  Start methimazole

2.  A 34-year-old man has polyuria (8 L/day), nocturia, and intense thirst 1 week after a traumatic brain injury. Serum Na is 149, serum osmolality is high, and urine osmolality is 110 mOsm/kg. During a water deprivation test, his urine stays dilute. After desmopressin, his urine osmolality rises to 540. What is the diagnosis and first-line treatment?

A.  Nephrogenic diabetes insipidus; hydrochlorothiazide

B.  Central diabetes insipidus; desmopressin (DDAVP)

C.  Primary polydipsia; fluid restriction

D.  SIADH; fluid restriction

E.  Central DI; demeclocycline

3.  A 34-year-old woman with vitiligo has 4 months of fatigue, weight loss, nausea, and salt craving. She has darkening of her palmar creases and buccal mucosa. BP is 92/58. Labs: Na 129, K 5.8, glucose 64. An 8 AM cortisol is 2.4 mcg/dL. Which additional finding is most expected?

A.  Low ACTH with normal renin

B.  Elevated ACTH (>100 pg/mL) with elevated plasma renin

C.  Low ACTH with suppressed renin

D.  Elevated ACTH with suppressed renin

E.  Normal ACTH with elevated aldosterone

4.  A 66-year-old man with type 2 diabetes and heart failure with reduced ejection fraction (EF 30%) is on metformin. His A1c is 8.1%. Which add-on agent is contraindicated because of fluid retention and worsening heart failure?

A.  Pioglitazone

B.  Empagliflozin

C.  Sitagliptin

D.  Glipizide

E.  Basal insulin

5.  A 45-year-old man has biochemically confirmed pheochromocytoma, and CT shows a 4-cm left adrenal mass. Adrenalectomy is planned. His BP is 178/104 and HR 102. Which preoperative regimen is most appropriate?

A.  Metoprolol alone for 2 weeks

B.  Phenoxybenzamine for 1–2 weeks, then add a beta blocker for tachycardia before surgery

C.  Propranolol first, then add phenoxybenzamine

D.  Proceed to surgery immediately without medication

E.  Hydrochlorothiazide and lisinopril

6.  An 80-year-old man with type 2 diabetes and CKD is started on glyburide. Two weeks later, his daughter finds him confused and diaphoretic, with a fingerstick glucose of 41 mg/dL. Which drug class most likely caused this, and why?

A.  Metformin — it causes lactic acidosis

B.  SGLT2 inhibitor — it causes euglycemic hypoglycemia

C.  GLP-1 agonist — it causes glucose-independent insulin release

D.  Sulfonylurea — it stimulates insulin release regardless of glucose level

E.  TZD — it causes insulin resistance

7.  A 58-year-old woman has recurrent kidney stones, diffuse bone pain, constipation, and depressed mood. Labs: calcium 11.6 mg/dL, phosphate 2.1 mg/dL (low), PTH elevated, elevated 24-hour urine calcium. Renal function is normal. What is the most likely cause and definitive treatment?

A.  Malignancy-associated hypercalcemia; bisphosphonates

B.  Parathyroid adenoma; parathyroidectomy

C.  Secondary hyperparathyroidism from CKD; cinacalcet

D.  Vitamin D deficiency; ergocalciferol

E.  Familial hypocalciuric hypercalcemia; observation

8.  A 78-year-old nursing-home resident with type 2 diabetes and a UTI has 5 days of increasing lethargy, then a seizure. She is severely dehydrated. Glucose 940 mg/dL, serum osmolality 356 mOsm/kg, HCO3 22, pH 7.38, anion gap 9, urine ketones trace. What is the diagnosis and first treatment priority?

A.  Hyperosmolar hyperglycemic state; aggressive IV 0.9% saline

B.  DKA; IV bicarbonate

C.  HHS; immediate high-dose IV insulin bolus before fluids

D.  Myxedema coma; IV levothyroxine

E.  SIADH; fluid restriction

9.  A 57-year-old woman with type 2 diabetes and obesity wants to add an injectable medication that promotes weight loss and reduces cardiovascular events. Her history includes a thyroidectomy for medullary thyroid carcinoma, and her brother has MEN2. Which drug class should be avoided?

A.  GLP-1 receptor agonists (e.g., semaglutide)

B.  Basal insulin

C.  DPP-4 inhibitors

D.  Sulfonylureas

E.  Metformin

10.  A 32-year-old woman with Graves disease started methimazole 6 weeks ago. She now has fever of 102.2°F, a severe sore throat, and mouth ulcers. What is the most appropriate next step?

A.  Stop methimazole immediately and check a CBC with differential

B.  Continue methimazole and start amoxicillin

C.  Double the methimazole dose

D.  Switch to radioactive iodine the same day

E.  Reassure; this is a viral pharyngitis

11.  A 41-year-old woman has weight gain, proximal muscle weakness, wide purple abdominal striae, easy bruising, a dorsocervical fat pad, and new hypertension. She takes no corticosteroids by any route. Which test is the gold standard to confirm hypercortisolism?

A.  Random serum cortisol

B.  24-hour urinary free cortisol

C.  Serum ACTH level

D.  High-dose dexamethasone suppression test

E.  Adrenal CT

12.  A 17-year-old boy is evaluated for infertility concerns and delayed puberty. He is tall with long limbs, has bilateral gynecomastia, sparse body hair, and small, firm testes. Which laboratory pattern is most expected?

A.  Low testosterone with low FSH and LH

B.  High testosterone with low FSH and LH

C.  Low testosterone with elevated FSH and LH

D.  Normal testosterone with elevated prolactin

E.  Elevated estrogen with low FSH and LH

13.  A 52-year-old obese man with newly diagnosed type 2 diabetes has polyuria, polydipsia, and a 7-kg unintentional weight loss over 2 months. HbA1c is 11.4% and glucose is 342 mg/dL. He is not in DKA or HHS. What is the most appropriate initial therapy?

A.  Metformin monotherapy alone and recheck in 3 months

B.  Diet and exercise alone for 3 months

C.  Start basal insulin (once-daily long-acting), along with lifestyle changes and likely metformin

D.  Sitagliptin monotherapy

E.  Acarbose monotherapy

14.  A 27-year-old woman has weight loss, tremor, and heat intolerance. Exam shows proptosis with lid lag, a smooth, diffusely enlarged, nontender goiter with a bruit, and raised pink-brown nonpitting plaques on her shins. TSH is undetectable, and FT4 and T3 are elevated. Which finding is the hallmark of the most likely diagnosis?

A.  Low radioactive iodine uptake

B.  Positive anti-TPO antibodies with low RAIU

C.  A single 'hot' nodule on scan with suppression of the rest of the gland

D.  Positive TSH receptor antibodies (TRAb) with diffusely increased RAIU

E.  Elevated TSH with a pituitary mass on MRI

15.  A 42-year-old woman has fatigue, cold intolerance, constipation, weight gain, dry coarse skin, and heavy periods. She has a firm, nontender goiter and delayed relaxation of her ankle reflexes. TSH is 18 mU/L, FT4 is low, and anti-TPO antibodies are positive. After starting levothyroxine, when should her TSH be rechecked?

A.  In 3 days

B.  In 1 week

C.  In 6 months

D.  Only if symptoms persist after 1 year

E.  4–6 weeks after starting therapy

16.  A 40-year-old man with untreated Graves disease is brought in 2 days after an emergency appendectomy. Temperature 105.1°F, HR 168 in atrial fibrillation, agitated and delirious, vomiting and diarrhea, new pulmonary edema. TSH undetectable, FT4 markedly elevated. Which sequence of management is correct?

A.  Propranolol, PTU, then potassium iodide 1 hour after PTU, plus IV hydrocortisone, cooling, and IV fluids; avoid aspirin

B.  Potassium iodide first, then PTU 1 hour later

C.  Aspirin for fever plus methimazole

D.  Immediate radioactive iodine ablation

E.  Levothyroxine and passive warming

17.  A 36-year-old woman has a 1.8-cm painless thyroid nodule found on exam. TSH is normal. Ultrasound shows a solid, hypoechoic nodule with irregular margins, microcalcifications, and taller-than-wide shape. What is the most appropriate next step?

A.  Radionuclide thyroid scan (RAIU)

B.  Repeat ultrasound in 12 months

C.  Start levothyroxine suppression therapy

D.  Serum calcitonin as the only test

E.  Fine-needle aspiration cytology

18.  A 62-year-old woman has a thyroid nodule and new bone pain in her pelvis. Imaging shows lytic bone lesions, and there are pulmonary nodules. The thyroid lesion shows uniform follicles with vascular and capsular invasion. Which type of thyroid cancer is most likely?

A.  Papillary carcinoma

B.  Medullary carcinoma

C.  Anaplastic carcinoma

D.  Follicular carcinoma

E.  Riedel thyroiditis

19.  In January, a 79-year-old woman who stopped her levothyroxine months ago is found at home confused and lethargic. Temperature 92.8°F, HR 46, BP 84/50, shallow respirations. She has periorbital edema and puffy facies. Glucose 58, Na 126, PaCO2 62. What is the most appropriate treatment in addition to airway and ventilatory support?

A.  Oral levothyroxine 25 mcg daily

B.  Active external rewarming with heating blankets alone

C.  IV methimazole

D.  IV levothyroxine plus IV liothyronine plus IV hydrocortisone, with passive rewarming and glucose correction

E.  IV hydrocortisone alone

20.  Two days after an uncomplicated radical neck dissection, a 55-year-old man has carpopedal spasm and perioral tingling. Inflating a BP cuff causes flexion of the wrist. Labs: calcium 6.9 mg/dL, phosphate 5.8 mg/dL, PTH low. ECG shows a prolonged QT. What is the most appropriate immediate treatment?

A.  IV calcium gluconate

B.  Oral calcium carbonate only

C.  Cinacalcet

D.  IV furosemide and normal saline

E.  Parathyroidectomy

21.  A 66-year-old man on hemodialysis for end-stage renal disease has bone pain. Labs: calcium 8.4 mg/dL (low-normal), phosphate 7.2 mg/dL (high), PTH markedly elevated. Which condition is most likely?

A.  Secondary hyperparathyroidism

B.  Primary hyperparathyroidism

C.  Tertiary hyperparathyroidism

D.  Hypoparathyroidism

E.  Pseudohypoparathyroidism

22.  FNA of a 2-cm thyroid nodule in a 33-year-old woman shows cells with empty-appearing 'Orphan Annie eye' nuclei, nuclear grooves, and psammoma bodies. Which statement is correct?

A.  This is anaplastic carcinoma with a very poor prognosis

B.  This is medullary carcinoma, which secretes calcitonin

C.  This is follicular carcinoma, diagnosed by capsular invasion on FNA

D.  This is benign; no treatment is needed

E.  This is papillary carcinoma, the most common thyroid cancer, with a good prognosis; treat with thyroidectomy, radioactive iodine, and TSH suppression

23.  A 19-year-old with type 1 diabetes has vomiting, abdominal pain, Kussmaul respirations, and fruity breath. Glucose 486, pH 7.12, HCO3 9, anion gap 26, serum ketones positive, K 3.0. A 1-liter normal saline bolus has been started. What is the most appropriate next step?

A.  Start an IV regular insulin infusion immediately

B.  Give IV sodium bicarbonate

C.  Start insulin and give potassium only if K falls below 2.5

D.  Hold insulin and give IV potassium chloride until K is above 3.3

E.  Switch to D5 0.45% saline

24.  A 26-year-old woman at 9 weeks' gestation has newly diagnosed Graves disease with tachycardia and weight loss. Which antithyroid drug is preferred at this stage of pregnancy?

A.  Methimazole

B.  Radioactive iodine ablation

C.  Potassium iodide alone

D.  Levothyroxine

E.  Propylthiouracil (PTU)

25.  A 58-year-old man stopped prednisone 30 mg daily abruptly 3 weeks ago after a 6-month course for polymyalgia rheumatica. He now has fatigue, myalgias, and anorexia. BP 104/66. Na 134, K 4.2. There is no hyperpigmentation. AM cortisol is low and ACTH is low-normal. What is the most appropriate long-term treatment if adrenal function doesn't recover?

A.  Hydrocortisone plus fludrocortisone

B.  Fludrocortisone alone

C.  Hydrocortisone alone

D.  Levothyroxine

E.  No treatment; symptoms will resolve

26.  A 67-year-old man with a 60-pack-year smoking history has nausea, headache, and muscle cramps. He appears euvolemic. Labs: Na 124 mEq/L, serum osmolality 258 mOsm/kg, urine osmolality 480 mOsm/kg, urine Na 46 mEq/L, uric acid 3.1 mg/dL. Thyroid and adrenal function are normal. CXR shows a hilar mass. What is the most appropriate initial treatment?

A.  Fluid restriction to under 1000 mL/day

B.  Rapid infusion of 3% hypertonic saline

C.  Normal saline at 200 mL/h alone

D.  Desmopressin

E.  Hydrochlorothiazide

27.  Which of the following patients meets diagnostic criteria for diabetes mellitus?

A.  A 45-year-old with a single HbA1c of 6.2%

B.  An asymptomatic 55-year-old with a random glucose of 185 mg/dL

C.  A 60-year-old with a 2-hour OGTT glucose of 168 mg/dL

D.  A 50-year-old with fasting plasma glucose of 131 and 128 mg/dL on two separate days

E.  A 40-year-old with a single fasting glucose of 118 mg/dL

28.  A 38-year-old woman has episodes of pounding headache, drenching sweats, and palpitations with BP of 210/120 during attacks. Between episodes, BP is 150/95. She has lost weight despite a good appetite. What is the best initial diagnostic test?

A.  Abdominal CT

B.  MIBG scan

C.  Serum TSH

D.  24-hour urine free cortisol

E.  Plasma fractionated metanephrines

29.  A 52-year-old man has progressive headaches and keeps bumping into door frames. Visual field testing shows bitemporal hemianopsia. Labs show normal prolactin and a mildly low cortisol. Which is the most likely cause and the most appropriate next step?

A.  Occipital lobe stroke; head CT

B.  Glaucoma; tonometry

C.  Multiple sclerosis; lumbar puncture

D.  Microprolactinoma; cabergoline alone

E.  Pituitary macroadenoma compressing the optic chiasm; MRI of the sella

30.  A 28-year-old woman has 8 months of amenorrhea, milky nipple discharge, and infertility. Pregnancy test is negative and TSH is normal. Prolactin is 210 ng/mL. MRI shows a 7-mm pituitary lesion. She has no visual symptoms. What is the most appropriate treatment?

A.  Transsphenoidal surgery

B.  Cabergoline (dopamine agonist)

C.  Radiation therapy

D.  Octreotide

E.  Levothyroxine

31.  A 44-year-old woman with poorly controlled diabetes has a sudden fever, chills, and severe unilateral right-sided neck pain with a fluctuant, tender thyroid mass. TSH and FT4 are normal. Ultrasound shows a 3-cm abscess, and FNA reveals neutrophils. What is the most appropriate treatment?

A.  Propranolol and NSAIDs only

B.  Methimazole

C.  Abscess drainage plus culture-directed antibiotics

D.  Levothyroxine

E.  Prednisone taper

32.  A 16-year-old boy has no signs of puberty: no facial hair, high-pitched voice, small testes. On review of systems, he says he has never been able to smell. Labs show low testosterone with low FSH and LH. What is the most likely diagnosis?

A.  Klinefelter syndrome

B.  Constitutional growth delay

C.  Prader-Willi syndrome

D.  Turner syndrome

E.  Kallmann syndrome

33.  An 11-year-old girl has 3 weeks of polyuria, polydipsia, increased appetite, and a 4-kg weight loss. She has perineal candidiasis. Random glucose is 342 mg/dL, and BMI is in the 40th percentile. Which laboratory profile is most expected?

A.  Low C-peptide and positive anti-GAD antibodies

B.  High C-peptide and negative antibodies

C.  High C-peptide and positive anti-TPO antibodies

D.  Normal C-peptide and elevated IGF-1

E.  Low C-peptide and negative antibodies with obesity

34.  A 42-year-old man has a thyroid nodule, chronic watery diarrhea, and facial flushing. His father died of a thyroid cancer and his sister had a pheochromocytoma. FNA shows C-cell-derived ovoid cells with amyloid stroma that stains with Congo red. Which tumor marker is used to monitor response to therapy?

A.  Thyroglobulin

B.  Alpha-fetoprotein

C.  Calcitonin and CEA

D.  Anti-TPO antibodies

E.  Serum metanephrines alone

35.  On the evening after a total thyroidectomy for papillary carcinoma, a 47-year-old woman reports perioral numbness and hand cramping. Tapping the facial nerve causes twitching of the mouth. Which complication occurred, and what other complication of this surgery should be assessed?

A.  Thyroid storm; assess for hyperthermia

B.  Hypercalcemia; assess for kidney stones

C.  Hypoglycemia; assess for adrenal insufficiency

D.  Hypocalcemia from parathyroid removal or injury; also assess for hoarseness from recurrent laryngeal nerve injury

E.  SIADH; assess for hyponatremia

36.  A 42-year-old woman with bipolar disorder on long-term lithium has polyuria (6 L/day) and polydipsia. Urine osmolality is 140 mOsm/kg and serum Na is 147. After a water deprivation test, desmopressin produces no change in urine osmolality. Besides addressing the lithium, which therapy is appropriate if symptoms persist?

A.  Desmopressin nasal spray

B.  Fluid restriction to 1 L/day

C.  Hydrochlorothiazide (or amiloride/indomethacin) with sodium and protein restriction

D.  Tolvaptan

E.  Carbamazepine

37.  A 37-year-old woman has confirmed hypercortisolism. Her ACTH is 64 pg/mL (elevated), and her cortisol suppresses by more than 50% after a high-dose dexamethasone suppression test. What is the most appropriate next step?

A.  CT of the chest to look for small cell lung cancer

B.  CT of the adrenal glands

C.  Bilateral adrenalectomy immediately

D.  Start ketoconazole as definitive therapy

E.  MRI of the pituitary, then transsphenoidal resection if an adenoma is found

38.  A 13-year-old boy is below the 5th percentile for height but has grown at a normal velocity, paralleling the 5th percentile since age 2. He has no signs of puberty. His father was a 'late bloomer' who grew until 19. Exam is otherwise normal. Wrist X-ray shows a delayed bone age. What is the most likely diagnosis?

A.  Familial short stature

B.  Growth hormone deficiency

C.  Constitutional growth delay

D.  Precocious puberty

E.  Achondroplasia

39.  A 48-year-old man has to resize his wedding ring and notes his shoe size has increased. His wife says his jaw and nose look larger, and he snores heavily. He has new hypertension and glucose intolerance. What is the best initial screening test?

A.  Random serum growth hormone

B.  Serum prolactin

C.  Serum IGF-1

D.  8 AM cortisol

E.  Pituitary MRI before any labs

40.  A 38-year-old woman had a URI 3 weeks ago and now has fever, malaise, and severe anterior neck pain radiating to her jaw. Her thyroid is diffusely enlarged and exquisitely tender. HR 112. TSH low, FT4 high, ESR 88 mm/h. Radioactive iodine uptake is low. What is the most appropriate management?

A.  Methimazole

B.  Radioactive iodine ablation

C.  NSAIDs or aspirin for pain, plus propranolol for adrenergic symptoms

D.  Total thyroidectomy

E.  IV antibiotics and drainage

41.  A 59-year-old woman started dapagliflozin 2 months ago for type 2 diabetes. She now reports vulvar itching with a thick white discharge. Which mechanism explains this adverse effect?

A.  Stimulation of pancreatic beta-cell insulin release

B.  Delayed intestinal glucose absorption

C.  Increased urinary glucose excretion from a lowered renal glucose threshold

D.  Increased peripheral insulin sensitivity

E.  Decreased hepatic gluconeogenesis

42.  A 72-year-old woman on sertraline is brought in after a generalized seizure. She is now obtunded. Na is 112 mEq/L, and she is euvolemic with concentrated urine. Hypertonic (3%) saline is started. Which complication is most important to avoid during correction?

A.  Cerebral edema from correcting sodium too slowly

B.  Hyperkalemia from hypertonic saline

C.  Diabetes insipidus from sertraline withdrawal

D.  Hypocalcemia from saline infusion

E.  Central pontine myelinolysis (osmotic demyelination) from correcting sodium too quickly

43.  A 64-year-old man with a 50-pack-year smoking history has 2 months of weight loss, proximal weakness, new hypertension, and edema. Labs: K 2.8, HCO3 33 (metabolic alkalosis), glucose 240. Cortisol is markedly elevated, ACTH is very high, and there is no suppression with high-dose dexamethasone. Which is the most likely cause?

A.  Pituitary corticotroph adenoma

B.  Cortisol-secreting adrenal adenoma

C.  Exogenous glucocorticoid use

D.  Primary hyperaldosteronism

E.  Ectopic ACTH production from small cell lung cancer

44.  A 31-year-old woman who is 3 months postpartum and breastfeeding has palpitations, anxiety, and heat intolerance. Her thyroid is not tender or enlarged. TSH is suppressed, FT4 is elevated, anti-TPO antibodies are positive, and Doppler ultrasound shows low flow. What is the most appropriate management?

A.  Methimazole for 12–18 months

B.  Radioactive iodine uptake scan and ablation

C.  Total thyroidectomy

D.  Propranolol for symptoms; no antithyroid drugs

E.  High-dose prednisone

45.  A 61-year-old man with type 2 diabetes on metformin 1000 mg BID is scheduled for a contrast-enhanced CT of the abdomen. His eGFR is 48. Which statement about metformin is correct?

A.  Hold metformin before iodinated contrast because of the risk of lactic acidosis

B.  Metformin should be doubled before contrast to prevent hyperglycemia

C.  Metformin's most common adverse effect is hypoglycemia

D.  Metformin causes weight gain and raises triglycerides

E.  Metformin is contraindicated in all patients over 60

46.  A 45-year-old woman with known Addison disease presents with 2 days of vomiting and diarrhea from gastroenteritis. She is confused, febrile, and has severe abdominal pain. BP 74/40, HR 124. Na 126, K 6.0, glucose 52. What is the most appropriate immediate management?

A.  Cosyntropin stimulation test before any steroids

B.  IV hydrocortisone 100 mg bolus plus IV normal saline with dextrose

C.  IV fludrocortisone plus IV fluids

D.  Oral hydrocortisone at double her usual dose

E.  IV norepinephrine alone

47.  A 54-year-old woman has a slowly enlarging, rock-hard, fixed, nontender goiter with neck pressure, dysphagia, and hoarseness. TSH and FT4 are normal. Doppler shows absent vascular flow. Biopsy shows dense, white, avascular fibrous tissue extending into the surrounding neck structures. What is the most likely diagnosis?

A.  Anaplastic thyroid carcinoma

B.  de Quervain thyroiditis

C.  Graves disease

D.  Riedel (invasive fibrous) thyroiditis

E.  Suppurative thyroiditis

48.  A 42-year-old man with type 1 diabetes on bedtime glargine reports high morning glucose (230s). A 3 AM glucose check shows 48 mg/dL with night sweats and nightmares. What is the most appropriate adjustment?

A.  Increase the bedtime glargine dose

B.  Decrease the nighttime long-acting insulin dose or add a bedtime snack

C.  Add a sulfonylurea at bedtime

D.  Move all insulin to the morning

E.  No change; this is the dawn phenomenon

49.  A patient being treated for DKA with IV normal saline and an insulin infusion now has a glucose of 198 mg/dL. The anion gap is 18, and the corrected sodium is 138. What is the most appropriate adjustment?

A.  Stop the insulin infusion because glucose is normalizing

B.  Change fluids to D5 with 0.45% saline and continue the insulin infusion

C.  Switch to subcutaneous insulin and discharge

D.  Continue 0.9% saline without dextrose and double the insulin

E.  Give 3% hypertonic saline

50.  A 29-year-old man with primary adrenal insufficiency on hydrocortisone and fludrocortisone calls the clinic. He has a fever of 101.5°F and a sinus infection, and was just started on amoxicillin-clavulanate. He is tolerating oral intake and has no vomiting. What is the correct advice?

A.  Continue the usual doses; no change is needed

B.  Double his oral hydrocortisone dose during the febrile illness

C.  Stop the fludrocortisone until the fever resolves

D.  Go to the ED for IV hydrocortisone

E.  Triple his fludrocortisone dose

Answer Key

Coverage: Thyroid 11  •  Parathyroid/SIADH 6  •  Adrenal 9  •  Diabetes 12  •  Gonadal 2  •  Endocrine Neoplasms 5  •  Pituitary 5

Answers & Clinical Rationales

1.  Answer: D. No thyroid hormone treatment; recheck after recovery (euthyroid sick syndrome)   [Thyroid]

Rationale: Euthyroid sick syndrome (nonthyroidal illness) is a change in thyroid tests, usually low, during severe illness or physiologic stress, common in the ICU. The gland itself functions normally. Altered deiodinase activity reduces T4-to-T3 conversion and increases reverse T3. 'Low T3 syndrome': low T3, normal T4 and TSH, normal or high rT3. A low T4 in prolonged illness indicates a poor prognosis. Thyroid hormone isn't indicated; recheck after recovery.

Why not the others: Replacing thyroid hormone doesn't help and may harm. A scan and methimazole have no role here.

2.  Answer: B. Central diabetes insipidus; desmopressin (DDAVP)   [Parathyroid/SIADH]

Rationale: Diabetes insipidus is an inability to concentrate urine: high serum osmolality, low urine osmolality and specific gravity, high urine volume. The water deprivation test establishes the diagnosis (urine stays dilute). The ADH (desmopressin) stimulation test distinguishes the types: central DI responds; nephrogenic DI doesn't. Central DI is the most common type; causes are idiopathic (most common), head trauma, CNS tumor, or infection. First-line treatment is desmopressin; carbamazepine is second line.

Why not the others: Nephrogenic DI wouldn't respond to desmopressin. Primary polydipsia concentrates urine with deprivation. SIADH causes hyponatremia. Demeclocycline induces nephrogenic DI and is used for SIADH.

3.  Answer: B. Elevated ACTH (>100 pg/mL) with elevated plasma renin   [Adrenal]

Rationale: This is primary adrenal insufficiency (Addison disease), most commonly autoimmune in the US (TB worldwide). Destruction of the adrenal cortex causes deficiency of cortisol, aldosterone, and androgens. Loss of negative feedback raises ACTH (>100 pg/mL), and ACTH's MSH activity causes hyperpigmentation. Hypoaldosteronism raises renin and causes hyponatremia, hyperkalemia, and metabolic acidosis. An 8 AM cortisol under 3 mcg/dL confirms adrenal insufficiency; 18 or higher rules it out. Anti-21-hydroxylase antibodies support the autoimmune cause.

Why not the others: A low or normal ACTH points to secondary adrenal insufficiency, which spares aldosterone (normal K, no hyperpigmentation). Suppressed renin and elevated aldosterone don't fit primary adrenal failure.

4.  Answer: A. Pioglitazone   [Diabetes]

Rationale: Thiazolidinediones (pioglitazone, rosiglitazone) increase peripheral insulin sensitivity. Adverse effects: peripheral edema, fluid retention, CHF, hepatotoxicity. Contraindications: heart failure, pregnancy, type 1 diabetes.

Why not the others: SGLT2 inhibitors like empagliflozin reduce CV risk and are favored in heart failure. Sitagliptin, glipizide, and insulin don't carry this specific contraindication.

5.  Answer: B. Phenoxybenzamine for 1–2 weeks, then add a beta blocker for tachycardia before surgery  [Adrenal]

Rationale: Complete adrenalectomy follows at least 1–2 weeks of medical therapy. Start with nonselective alpha blockade (phenoxybenzamine or phentolamine) for 1–2 weeks, then add a beta blocker or CCB for BP and heart rate control. Do NOT start with beta blockade: it leaves alpha-mediated vasoconstriction unopposed and can cause a life-threatening hypertensive crisis, especially when surgery triggers catecholamine release.

Why not the others: Beta blocker monotherapy or beta-first sequencing risks hypertensive crisis. Unblocked surgery is dangerous. Diuretics and ACE inhibitors don't block catecholamine effects.

6.  Answer: D. Sulfonylurea — it stimulates insulin release regardless of glucose level   [Diabetes]

Rationale: Sulfonylureas (glipizide, glyburide, glimepiride; first generation: tolbutamide, chlorpropamide) stimulate pancreatic beta-cell insulin release. Their main adverse effect is hypoglycemia, a particular risk in the elderly and in CKD, where clearance is reduced. Chlorpropamide can also cause hyponatremia and a disulfiram-like reaction. Meglitinides share the mechanism and also cause hypoglycemia and weight gain.

Why not the others: Metformin, SGLT2 inhibitors, GLP-1 agonists (whose insulin release is glucose-dependent), and TZDs rarely cause hypoglycemia on their own.

7.  Answer: B. Parathyroid adenoma; parathyroidectomy   [Parathyroid/SIADH]

Rationale: Primary hyperparathyroidism triad: hypercalcemia, elevated PTH, low phosphate, with elevated 24-hour urine calcium. A parathyroid adenoma is the most common cause; others are hyperplasia, lithium, and MEN1/MEN2a. Symptoms: 'stones, bones, abdominal groans, psychiatric moans,' plus weakness and decreased DTRs. Definitive treatment is parathyroidectomy (cinacalcet if not a surgical candidate). Localize with ultrasound or nuclear (sestamibi) scanning. For very high calcium: IV fluids, furosemide, calcitonin.

Why not the others: Malignancy suppresses PTH. Secondary hyperparathyroidism has normal or low calcium with high phosphate. Vitamin D deficiency causes low calcium. Familial hypocalciuric hypercalcemia has LOW urine calcium.

8.  Answer: A. Hyperosmolar hyperglycemic state; aggressive IV 0.9% saline   [Diabetes]

Rationale: HHS is more common than DKA in elderly type 2 diabetics. Enough insulin is secreted to suppress lipolysis and ketogenesis, so there's profound dehydration and hyperosmolarity without significant ketoacidosis. Onset is insidious (days), with neurologic symptoms (lethargy, focal deficits, seizures) and no abdominal pain, fruity breath, or Kussmaul breathing. Diagnosis: glucose over 600, osmolality over 320, HCO3 over 18, pH over 7.4 (or near-normal), normal anion gap, and negative or small ketones. Fluids are the most important treatment: start with 0.9% NaCl, switch to D5NS at glucose of about 300, and follow the same insulin and K rules as DKA.

Why not the others: No acidosis or ketosis rules out DKA. Insulin before volume can cause cardiovascular collapse. The other diagnoses don't fit.

9.  Answer: A. GLP-1 receptor agonists (e.g., semaglutide)   [Diabetes]

Rationale: GLP-1 agonists (liraglutide, semaglutide, dulaglutide) increase glucose-dependent insulin secretion and offer weight loss and CV event reduction. Adverse effects: GI upset, pancreatitis. Contraindications: history of gastroparesis or pancreatitis, and medullary thyroid cancer (personal or family history, MEN2), based on C-cell tumors in animal studies.

Why not the others: Insulin, sulfonylureas, metformin, and DPP-4 inhibitors don't carry the medullary thyroid cancer contraindication. (DPP-4 inhibitors do carry a pancreatitis warning.)

10.  Answer: A. Stop methimazole immediately and check a CBC with differential   [Thyroid]

Rationale: Antithyroid drug adverse effects: hypersensitivity, agranulocytosis (rare but life-threatening), aplastic anemia, thrombocytopenia, dysgeusia, teratogenicity (methimazole), and hepatotoxicity (PTU). Fever and sore throat on methimazole suggest agranulocytosis. Stop the drug and check a CBC with differential immediately; if the patient is neutropenic and febrile, treat as neutropenic fever.

Why not the others: Continuing or raising the dose risks overwhelming infection. Same-day RAI isn't appropriate in an acutely ill patient. You can't assume viral pharyngitis on an antithyroid drug.

11.  Answer: B. 24-hour urinary free cortisol   [Adrenal]

Rationale: First rule out exogenous Cushing syndrome, the most common cause. Then confirm hypercortisolism with a screening test: 24-hour urinary free cortisol (gold standard; positive at 3x the ULN or more on 2 or more collections), late-night salivary cortisol (elevated on 2 or more measurements), or the overnight 1-mg low-dose dexamethasone suppression test (no AM cortisol suppression is positive). Only after confirmation do you localize the cause with ACTH and high-dose dexamethasone.

Why not the others: A random cortisol is unreliable because of diurnal variation. ACTH and the high-dose dexamethasone test localize the source after hypercortisolism is confirmed. Imaging comes last.

12.  Answer: C. Low testosterone with elevated FSH and LH   [Gonadal]

Rationale: Klinefelter syndrome (47,XXY) causes primary (hypergonadotropic) hypogonadism. Gonadal failure means low testosterone, and the lost negative feedback raises FSH and LH. Features: testicular hypoplasia, gynecomastia, decreased body hair, infertility. Diagnosis includes testosterone under 300 ng/dL and a karyotype. Treatment is testosterone replacement.

Why not the others: Low FSH and LH indicate secondary (hypogonadotropic) disease, such as Kallmann syndrome. The other patterns don't fit testicular failure.

13.  Answer: C. Start basal insulin (once-daily long-acting), along with lifestyle changes and likely metformin   [Diabetes]

Rationale: Metformin is first-line for type 2 diabetes. Consider insulin in newly diagnosed patients with an initial glucose of 300 or higher or A1c over 10%, symptomatic hyperglycemia, or signs of a catabolic state (weight loss). Start with a basal insulin regimen with once-daily injections. Other insulin indications: glycemic targets unmet on other drugs, gestational diabetes, hyperglycemic crisis.

Why not the others: Metformin alone or lifestyle changes alone won't control symptomatic, catabolic hyperglycemia with A1c over 10%. DPP-4 inhibitors and acarbose are weak options for this degree of hyperglycemia.

14.  Answer: D. Positive TSH receptor antibodies (TRAb) with diffusely increased RAIU   [Thyroid]

Rationale: Graves disease is the most common cause of hyperthyroidism. It's a type II hypersensitivity: TSH-receptor antibodies (TRAb, the hallmark) stimulate hormone production and gland growth. Peak age 20–30; women outnumber men 8:1. Unique triad: diffuse goiter (with or without bruit), ophthalmopathy (exophthalmos, diplopia, lid retraction), and pretibial myxedema. RAIU is diffusely increased.

Why not the others: Low uptake suggests thyroiditis. A single hot nodule is a toxic adenoma. Elevated TSH with a pituitary mass is a TSH-secreting adenoma. Anti-TPO with low uptake is painless or postpartum thyroiditis.

15.  Answer: E. 4–6 weeks after starting therapy   [Thyroid]

Rationale: Hashimoto thyroiditis is the most common cause of hypothyroidism (iodine deficiency worldwide). It's autoimmune (anti-TPO and TgAb), with women outnumbering men 7:1, most common at ages 30–50. Treatment is lifelong levothyroxine (synthetic T4) taken every morning 1 hour before breakfast. Check TSH 4–6 weeks after starting or changing the dose until it normalizes, then 4–6 months after normal TSH is achieved, then annually. Levothyroxine's long half-life means steady state takes about 6 weeks.

Why not the others: Checking at 3 days or 1 week is too early to reflect steady state. Six months or a year delays titration.

16.  Answer: A. Propranolol, PTU, then potassium iodide 1 hour after PTU, plus IV hydrocortisone, cooling, and IV fluids; avoid aspirin   [Thyroid]

Rationale: Thyroid storm is a life-threatening hypermetabolic state triggered by surgery, trauma, infection, an iodine load, or stopping antithyroid drugs. Features: tachycardia over 140 or AFib, CHF, hyperpyrexia (104–106°F), agitation or delirium, GI symptoms. Treatment: propranolol; cooling blankets and antipyretics (AVOID aspirin, which raises free T4/T3); IV fluids with dextrose; benzodiazepines for agitation; PTU, then potassium iodide 1 hour later (giving iodide first supplies substrate for more hormone); and IV hydrocortisone (blocks T4-to-T3 conversion).

Why not the others: Iodide before PTU fuels hormone synthesis. Aspirin displaces hormone from binding proteins. RAI is too slow and can worsen thyrotoxicosis. Levothyroxine and warming are for myxedema coma.

17.  Answer: E. Fine-needle aspiration cytology   [Endocrine Neoplasms]

Rationale: Initial thyroid nodule evaluation is a TSH and ultrasound. High-risk ultrasound features (solid, hypoechoic, irregular margins, microcalcifications, taller than wide) warrant FNA cytology, the confirmatory diagnostic test. A radionuclide scan is indicated only when TSH is LOW, to look for a hyperfunctioning 'hot' nodule; cold nodules carry higher risk.

Why not the others: A scan is for suppressed TSH. Watching a high-risk nodule delays diagnosis. Levothyroxine suppression isn't a diagnostic step. Calcitonin alone doesn't diagnose the nodule type.

18.  Answer: D. Follicular carcinoma   [Endocrine Neoplasms]

Rationale: Follicular carcinoma ('follicular goes far') spreads hematogenously, with distant metastases especially to lung and bone (lytic lesions). It generally has a good prognosis. Diagnosis requires capsular or vascular invasion on histology. Thyroglobulin is monitored after thyroidectomy and RAI.

Why not the others: Papillary spreads to lymph nodes. Medullary arises from C cells. Anaplastic shows giant cells with rapid local compression. Riedel thyroiditis is fibrotic, not malignant.

19.  Answer: D. IV levothyroxine plus IV liothyronine plus IV hydrocortisone, with passive rewarming and glucose correction   [Thyroid]

Rationale: Myxedema coma is a rare, life-threatening decompensation of hypothyroidism, often in elderly women in winter, triggered by cold, infection, sedatives, or stopping levothyroxine. Cardinal signs: altered mental status, hypothermia, myxedema; also hypotension, bradycardia, hypoventilation with hypercapnia, hyponatremia, hypoglycemia. Treatment: airway and fluids, passive warming, ventilatory support, treat hypoglycemia, IV levothyroxine plus IV liothyronine (T3), and hydrocortisone until coexisting adrenal insufficiency is excluded. Mortality is up to 60%.

Why not the others: Low-dose oral replacement is too slow and poorly absorbed. Active rewarming can cause vasodilatory collapse. Methimazole is for hyperthyroidism. Hydrocortisone alone doesn't replace thyroid hormone.

20.  Answer: A. IV calcium gluconate   [Parathyroid/SIADH]

Rationale: Hypoparathyroidism triad: hypocalcemia, low PTH, high phosphate. Most common causes: post-neck surgery and autoimmune; also radiation and hypomagnesemia. Signs: carpopedal spasm, perioral numbness, increased DTRs, Trousseau (carpal spasm with BP cuff) and Chvostek signs, prolonged QT. Acute symptomatic hypocalcemia gets IV calcium gluconate. Long-term: calcium supplements plus calcitriol (active vitamin D).

Why not the others: Oral calcium alone is too slow for symptomatic hypocalcemia with QT prolongation. Cinacalcet, furosemide with saline, and parathyroidectomy treat hypercalcemia.

21.  Answer: A. Secondary hyperparathyroidism   [Parathyroid/SIADH]

Rationale: PTH patterns: primary has high calcium, low phosphate, high PTH. Secondary has normal or low calcium, high phosphate, high PTH (classically CKD, where phosphate retention and low active vitamin D drive PTH up). Tertiary has high calcium, high phosphate, high PTH (autonomous glands after long-standing secondary disease).

Why not the others: Primary has high calcium and low phosphate. Tertiary has high calcium. Hypoparathyroidism has low PTH. Pseudohypoparathyroidism has high PTH but low calcium with end-organ resistance; it isn't the classic CKD picture.

22.  Answer: E. This is papillary carcinoma, the most common thyroid cancer, with a good prognosis; treat with thyroidectomy, radioactive iodine, and TSH suppression   [Endocrine Neoplasms]

Rationale: Papillary carcinoma ('papillary is popular') is the most common thyroid cancer. Histology: psammoma bodies, Orphan Annie eye nuclei, nuclear grooves. It spreads to cervical lymph nodes and has a good prognosis. Treatment for well-differentiated cancer: total thyroidectomy (with neck dissection as needed), radioactive iodine ablation, and TSH suppression with L-thyroxine. Thyroglobulin is monitored after treatment.

Why not the others: The described histology isn't anaplastic (giant cells, necrosis), medullary (C cells, amyloid), or follicular (capsular or vascular invasion, which FNA can't assess).

23.  Answer: D. Hold insulin and give IV potassium chloride until K is above 3.3   [Diabetes]

Rationale: In DKA, insulin deficiency drives K out of cells, so serum K can look normal or high despite a total-body deficit. Insulin then shifts K back in and can cause fatal hypokalemia. Rules: K under 3.3, hold insulin and give IV KCl until K is above 3.3. K 3.3–5.2: give KCl with insulin, keeping K at 4–5. K above 5.2: no K repletion. Once insulin starts, the goal is to lower glucose about 10% per hour. Bicarbonate is given only if pH is below 6.9 despite fluids.

Why not the others: Insulin now risks arrhythmia. Bicarbonate isn't indicated at pH 7.12. Dextrose is added at glucose of about 200.

24.  Answer: E. Propylthiouracil (PTU)   [Thyroid]

Rationale: Methimazole is the drug of choice for hyperthyroidism generally, but PTU is preferred in the first trimester because methimazole is teratogenic. PTU's main risk is hepatotoxicity, so patients typically switch to methimazole after the first trimester. RAI is contraindicated in pregnancy, breastfeeding, or planned pregnancy within 4–6 months.

Why not the others: Methimazole is teratogenic in the first trimester. RAI is contraindicated. Iodide alone isn't maintenance therapy. Levothyroxine treats hypothyroidism.

25.  Answer: C. Hydrocortisone alone   [Adrenal]

Rationale: This is secondary adrenal insufficiency. Exogenous steroids are the most common cause, suppressing the HPA axis so ACTH is low and only cortisol is deficient. Aldosterone is regulated by renin-angiotensin, not ACTH, so it's preserved: normal potassium and no salt wasting. With no ACTH excess, there's no hyperpigmentation. Treatment is glucocorticoid replacement only. Prevention: taper steroids after prolonged therapy.

Why not the others: Fludrocortisone is added only in primary (Addison) disease, where aldosterone is lost. Levothyroxine doesn't treat cortisol deficiency. Symptomatic HPA suppression needs replacement.

26.  Answer: A. Fluid restriction to under 1000 mL/day   [Parathyroid/SIADH]

Rationale: This is SIADH, likely paraneoplastic ectopic ADH from small cell lung cancer. Excess ADH inserts aquaporin-2 channels, causing water retention, euvolemic hyponatremia, low serum osmolality (under 275), inappropriately concentrated urine (over 100), urine Na over 20–30, and low uric acid (under 4). Other causes: CNS disease, carbamazepine, SSRIs, cyclophosphamide. Mild to moderate symptoms: fluid restriction first; refractory cases get vaptans (tolvaptan, conivaptan), urea, or demeclocycline.

Why not the others: Hypertonic saline is for severe symptoms (seizures, altered consciousness). Normal saline alone can worsen SIADH hyponatremia. Desmopressin is ADH and would worsen it. Thiazides cause hyponatremia.

27.  Answer: D. A 50-year-old with fasting plasma glucose of 131 and 128 mg/dL on two separate days   [Diabetes]

Rationale: Diabetes criteria (any one): random glucose 200 or higher with classic symptoms; fasting plasma glucose 126 or higher on more than one occasion; 2-hour glucose 200 or higher after a 75-g OGTT; or HbA1c 6.5% or higher confirmed by repeat testing. Two fasting values of 126 or higher meet criteria.

Why not the others: An A1c of 6.2%, a random glucose of 185 without symptoms, a 2-hour OGTT of 168, and a fasting glucose of 118 are all below the diagnostic thresholds (prediabetic range).

28.  Answer: E. Plasma fractionated metanephrines   [Adrenal]

Rationale: This is pheochromocytoma, a catecholamine-secreting tumor of adrenal chromaffin cells. Classic triad: headache, sweating, palpitations, with hypertension as the most consistent finding. Biochemical testing comes first: plasma fractionated metanephrines, confirmed by 24-hour urinary fractionated catecholamines and metabolites (elevated metanephrines and VMA). Then image the abdomen and pelvis with CT or MRI. An MIBG scan finds extra-adrenal tumors when CT/MRI is negative. Rule of 10s: 10% malignant, bilateral, pediatric, and extra-adrenal. Associations: MEN2, NF1, von Hippel-Lindau.

Why not the others: Imaging comes after biochemical confirmation. MIBG is for extra-adrenal tumors. TSH and urine cortisol test other diseases.

29.  Answer: E. Pituitary macroadenoma compressing the optic chiasm; MRI of the sella   [Pituitary]

Rationale: Pituitary adenomas over 1 cm (macroadenomas) can compress the optic chiasm, causing bitemporal hemianopsia and headache. Nonsecreting adenomas (about a third) present with mass effect and hypopituitarism. Evaluate with an MRI of the sella and endocrine studies (prolactin, GH/IGF-1, ACTH/cortisol, TSH, LH/FSH). Compressive tumors are treated with transsphenoidal surgery.

Why not the others: A stroke causes homonymous, not bitemporal, defects. Glaucoma and MS don't cause this pattern. Prolactin is normal, so this isn't a prolactinoma.

30.  Answer: B. Cabergoline (dopamine agonist)   [Pituitary]

Rationale: Prolactinoma is the most common pituitary adenoma (about 50%), causing amenorrhea, galactorrhea, and infertility. Under 1 cm is a microadenoma; over 1 cm is a macroadenoma. Prolactinomas are managed medically first with dopamine agonists (cabergoline, bromocriptine). Transsphenoidal surgery is first-line for other active or compressive tumors, or prolactinomas that fail medical therapy.

Why not the others: Surgery and radiation aren't first-line for prolactinoma. Octreotide is for GH-secreting tumors. TSH is normal, so levothyroxine isn't indicated.

31.  Answer: C. Abscess drainage plus culture-directed antibiotics   [Thyroid]

Rationale: Infectious (suppurative) thyroiditis is caused by gram-positive or gram-negative organisms reaching the thyroid hematogenously, usually in immunocompromised patients; Staphylococcus and Streptococcus are the most common causes. Acute presentation: sudden unilateral neck pain, fever, chills, and an often fluctuant mass. Thyroid function is usually normal. Diagnosis: ultrasound (abscess) and FNA with stain and culture. Treatment: drainage plus antibiotics based on culture.

Why not the others: Symptomatic therapy, antithyroid drugs, levothyroxine, and steroids don't treat an abscess.

32.  Answer: E. Kallmann syndrome   [Gonadal]

Rationale: Kallmann syndrome is hypogonadotropic (secondary) hypogonadism. Impaired GnRH neuron migration and a defective olfactory bulb cause low GnRH, low FSH/LH, and low sex hormones. Hallmark: anosmia. Other features: cleft lip or palate, syndactyly. Treatment: pulsatile LHRH or hCG in males (improves fertility and triggers puberty), or testosterone.

Why not the others: Klinefelter has high FSH and LH. Constitutional delay has no anosmia. Prader-Willi features hypotonia, short stature, and dysmorphia. Turner syndrome affects females.

33.  Answer: A. Low C-peptide and positive anti-GAD antibodies   [Diabetes]

Rationale: Type 1 diabetes is autoimmune destruction of pancreatic beta cells (HLA-DR3/DR4, not associated with obesity), causing absolute insulin deficiency. Onset is usually before 20, peaking at ages 4–6 and 10–14. Labs show low insulin and C-peptide and positive autoantibodies (anti-GAD, IA-2, ICA). About a third present in DKA. Perineal candidiasis is common in young girls. Treatment is insulin.

Why not the others: High C-peptide with negative antibodies suggests type 2 diabetes. Anti-TPO is a thyroid antibody, and IGF-1 relates to acromegaly. The patient isn't obese.

34.  Answer: C. Calcitonin and CEA   [Endocrine Neoplasms]

Rationale: Medullary thyroid carcinoma arises from parafollicular C cells. Most cases are sporadic (75%); 25% are associated with MEN2 (with pheochromocytoma). It produces calcitonin, which causes diarrhea and flushing. Histology: amyloid stroma staining with Congo red. Markers: calcitonin and CEA. Treatment: total thyroidectomy plus neck dissection, with or without radiation or chemotherapy. Screen for pheochromocytoma before surgery in MEN2.

Why not the others: Thyroglobulin monitors papillary and follicular cancer. AFP and anti-TPO aren't relevant. Metanephrines screen for the associated pheochromocytoma but don't monitor the thyroid cancer.

35.  Answer: D. Hypocalcemia from parathyroid removal or injury; also assess for hoarseness from recurrent laryngeal nerve injury   [Endocrine Neoplasms]

Rationale: Complications of thyroid surgery: hypocalcemia from removal of or injury to the parathyroids (postoperative hypoparathyroidism is the most common complication), with perioral numbness, carpopedal spasm, Chvostek and Trousseau signs, and a prolonged QT. Also assess for hoarseness or dysphagia from recurrent laryngeal nerve damage, and postoperative hypothyroidism. Acute symptomatic hypocalcemia gets IV calcium gluconate.

Why not the others: Thyroid storm, hypercalcemia, hypoglycemia, and SIADH don't cause these findings.

36.  Answer: C. Hydrochlorothiazide (or amiloride/indomethacin) with sodium and protein restriction   [Pituitary]

Rationale: Nephrogenic DI is partial or complete renal insensitivity to ADH. Causes: lithium, amphotericin B, hypokalemia, hypercalcemia, ATN, hyperparathyroidism. It doesn't respond to desmopressin. Treat the underlying cause; if symptoms persist, use HCTZ, indomethacin, or amiloride (amiloride is especially useful for lithium-induced DI), plus sodium and protein restriction.

Why not the others: Desmopressin and carbamazepine treat central DI. Fluid restriction risks severe hypernatremia. Tolvaptan is a vaptan for SIADH and would worsen DI.

37.  Answer: E. MRI of the pituitary, then transsphenoidal resection if an adenoma is found   [Adrenal]

Rationale: High ACTH plus suppression with high-dose dexamethasone means Cushing DISEASE, a pituitary ACTH-secreting adenoma. It's the most common endogenous cause (about 75%) and causes bilateral adrenal hyperplasia. A pituitary MRI confirms the adenoma, and transsphenoidal resection is first-line treatment (radiation or pasireotide if inoperable). Ectopic ACTH: high ACTH with no suppression; image to find the tumor. Adrenal tumor: low ACTH (<5) with no suppression; adrenal CT.

Why not the others: A chest CT is for ectopic ACTH (no suppression). Adrenal CT is for ACTH-independent disease. Adrenalectomy and ketoconazole are for inoperable or refractory cases.

38.  Answer: C. Constitutional growth delay   [Pituitary]

Rationale: Bone age on an AP X-ray of the left wrist differentiates the causes. Delayed bone age: constitutional delay, where children grow at or below the 5th percentile at a normal velocity, puberty is delayed, and there's often a family history of late puberty. Normal bone age: familial short stature, where puberty occurs on time. Advanced bone age: precocious puberty. Disproportionate short stature (short limbs) suggests achondroplasia or rickets.

Why not the others: Familial short stature has a normal bone age. GH deficiency causes slowed growth velocity. Precocious puberty causes advanced bone age. Achondroplasia is disproportionate.

39.  Answer: C. Serum IGF-1   [Pituitary]

Rationale: Acromegaly (adults, after growth plates fuse) and gigantism (children) are most often caused by a GH-secreting pituitary adenoma. Features: enlarged hands, feet, nose, lips, ears, jaw, and tongue. Screen with IGF-1 (stable, reflects integrated GH). Confirm with failure of GH suppression 2 hours after an oral glucose load. Then pituitary MRI. Treatment: transsphenoidal surgery, with dopamine agonists (bromocriptine) as adjuncts.

Why not the others: Random GH is unreliable because secretion is pulsatile. Prolactin and cortisol test other adenomas. Imaging follows biochemical confirmation.

40.  Answer: C. NSAIDs or aspirin for pain, plus propranolol for adrenergic symptoms   [Thyroid]

Rationale: Subacute granulomatous (de Quervain) thyroiditis is a viral or post-viral inflammatory process (associated with HLA-B35), often after a URI. It causes a painful, tender, diffusely enlarged thyroid. Phases: transient hyperthyroid (2–8 weeks), transient hypothyroid, then recovery (permanent hypothyroidism in about 15%). Diagnosis: very high ESR, low RAIU, negative antibodies. Treatment: ASA or NSAIDs (prednisone if severe), propranolol for hyperthyroid symptoms, and levothyroxine for 6–8 weeks if TSH exceeds 10.

Why not the others: Antithyroid drugs and RAI don't work because the thyrotoxicosis comes from leakage of stored hormone, not overproduction (low RAIU). Surgery and antibiotics aren't indicated for de Quervain.

41.  Answer: C. Increased urinary glucose excretion from a lowered renal glucose threshold   [Diabetes]

Rationale: SGLT2 inhibitors (empagliflozin, canagliflozin, dapagliflozin) lower the renal glucose threshold, so more glucose is excreted in the urine. Glucosuria predisposes to genital yeast infections and UTIs. Other adverse effects: transient nausea and vomiting. They reduce CV risk and are contraindicated in type 1 diabetes.

Why not the others: Beta-cell stimulation is the sulfonylurea/meglitinide mechanism, delayed intestinal absorption is acarbose, insulin sensitization is TZDs, and decreased hepatic output is metformin. None of these cause glucosuria.

42.  Answer: E. Central pontine myelinolysis (osmotic demyelination) from correcting sodium too quickly  [Parathyroid/SIADH]

Rationale: Severe symptomatic hyponatremia (seizures, altered consciousness) is treated with hypertonic 3% saline. SSRIs like sertraline are a classic SIADH cause. Correcting sodium too quickly causes central pontine myelinolysis (osmotic demyelination), so correction must be limited (generally no more than 8 mEq/L in 24 hours).

Why not the others: Slow correction doesn't cause cerebral edema; rapid drops in sodium do. The other complications aren't typical of hypertonic saline.

43.  Answer: E. Ectopic ACTH production from small cell lung cancer   [Adrenal]

Rationale: High ACTH without suppression on high-dose dexamethasone means ectopic ACTH. Small cell lung cancer is the most common source (carcinoid tumors are another), via a paraneoplastic syndrome that causes bilateral adrenal hyperplasia. Very high cortisol acts like a mineralocorticoid, causing hypokalemia, metabolic alkalosis, and hypertension; hyperglycemia is common. Image (CXR, CT, PET) to find the tumor.

Why not the others: A pituitary adenoma suppresses with high-dose dexamethasone. An adrenal adenoma and exogenous steroids cause low ACTH. Primary hyperaldosteronism doesn't raise cortisol or ACTH.

44.  Answer: D. Propranolol for symptoms; no antithyroid drugs   [Thyroid]

Rationale: Postpartum thyroiditis is a destructive, autoimmune (Hashimoto variant, anti-TPO positive) painless thyroiditis within a year of delivery or abortion. It may be hyperthyroid only, hypothyroid only, or hyperthyroid then hypothyroid then recovery. The hyperthyroid phase is from hormone release, not synthesis, so there's no role for antithyroid drugs; treat symptoms with propranolol. RAIU shows low uptake but is contraindicated while breastfeeding. Give levothyroxine if hypothyroid symptoms appear or TSH exceeds 10. Up to 30% develop permanent hypothyroidism.

Why not the others: Methimazole doesn't treat a destructive thyroiditis. RAI is contraindicated in breastfeeding. Surgery and steroids aren't indicated.

45.  Answer: A. Hold metformin before iodinated contrast because of the risk of lactic acidosis   [Diabetes]

Rationale: Metformin (a biguanide) lowers hepatic glucose production. It's first-line oral therapy for type 2 diabetes, with weight loss, lower triglycerides, and lower CV risk. Its most common adverse effects are GI (nausea, vomiting, diarrhea); others are B12 deficiency and lactic acidosis. Contraindications: severe renal or hepatic impairment. Hold it before iodinated contrast.

Why not the others: Metformin alone rarely causes hypoglycemia, causes weight loss rather than gain, and isn't contraindicated by age alone.

46.  Answer: B. IV hydrocortisone 100 mg bolus plus IV normal saline with dextrose   [Adrenal]

Rationale: This is an adrenal (Addisonian) crisis, an emergency usually triggered by stress (GI illness, infection, surgery) or abrupt steroid withdrawal. Treat immediately and do endocrine testing once the patient is stable: IV hydrocortisone 100 mg bolus, then 50 mg q6h, plus IV fluids with dextrose. Mineralocorticoid replacement isn't needed acutely: high-dose hydrocortisone has mineralocorticoid activity, fludrocortisone takes days to work, and IV saline replaces the sodium.

Why not the others: Testing shouldn't delay treatment in a crisis. Fludrocortisone isn't given IV or acutely. Oral doses won't absorb with vomiting. Pressors without steroids won't reverse the shock.

47.  Answer: D. Riedel (invasive fibrous) thyroiditis   [Thyroid]

Rationale: Riedel thyroiditis is part of the IgG4-related disease spectrum. Extensive fibrosis with macrophage and eosinophil infiltration extends into adjacent tissues, producing a hard, fixed, nontender goiter with compressive symptoms. TFTs are usually normal, and two-thirds are anti-TPO/TgAb positive. Diagnosis is by biopsy. Treatment: prednisone to shrink and soften the mass, surgery for compression, levothyroxine if hypothyroid, and rituximab or mycophenolate for IgG4 disease.

Why not the others: Anaplastic carcinoma shows giant cells and necrosis. De Quervain is tender with a high ESR. Graves causes hyperthyroidism. Suppurative thyroiditis causes a painful, fluctuant, febrile mass.

48.  Answer: B. Decrease the nighttime long-acting insulin dose or add a bedtime snack   [Diabetes]

Rationale: This pattern is the Somogyi effect: nocturnal hypoglycemia followed by rebound morning hyperglycemia (attributed to a GH surge; evidence for it is debated). Treatment is decreasing the nighttime long-acting dose or giving a bedtime snack. By contrast, the dawn phenomenon has normal glucose until about 2–8 AM, then a rise from counter-regulatory hormones, and is treated with bedtime long-acting insulin and no late carbs. Insulin waning is a progressive rise from bedtime to morning, treated by moving the dose to bedtime. The 3 AM check distinguishes them.

Why not the others: Increasing glargine worsens nocturnal hypoglycemia. Sulfonylureas aren't used in type 1. A low 3 AM glucose rules out the dawn phenomenon.

49.  Answer: B. Change fluids to D5 with 0.45% saline and continue the insulin infusion   [Diabetes]

Rationale: DKA fluids: 0.9% NaCl in the first hour, then check the corrected sodium. If corrected Na is 135 or higher, switch to 0.45% NaCl; if below 135, continue normal saline. Add dextrose when glucose falls to about 200 mg/dL so insulin can keep running until the ketoacidosis (anion gap) resolves without causing hypoglycemia. The goal is closing the gap, not just normalizing glucose.

Why not the others: Stopping insulin or transitioning early while the gap is still open lets ketoacidosis recur. Doubling insulin without dextrose causes hypoglycemia. Hypertonic saline isn't indicated.

50.  Answer: B. Double his oral hydrocortisone dose during the febrile illness   [Adrenal]

Rationale: Stress dosing ('sick day rules') prevents adrenal crisis. Double the oral glucocorticoid dose for fever, illness needing bed rest, or illness needing antibiotics. IM or IV glucocorticoids are needed for intractable vomiting or diarrhea, trauma, or surgery. The mineralocorticoid dose isn't stress-adjusted.

Why not the others: Making no change risks crisis. Stopping fludrocortisone is wrong. IV steroids are for patients who can't keep oral doses down. Fludrocortisone isn't the stress-dose drug.