B6: Cell Bio PQ's (copy)

it has a plasma binding that greatly reduces its bioavailability

A 34 year old female presents to the office after recovery from a traumatic head injury with a complaint of excessive thirst and urination.

After confirming the diagnosis as a central disorder of a hormone secreting neural structure, what is untrue about the problematic hormone?

TSH, FSH, LH

To combat a hCG secreting tumor, a 34 year old male is given antibodies which react to the alpha subunit of the hCG hormone.

Which other hormones’ actions will be directly inhibited by the antibodies?

tyrosine

A 46 year old woman presents to the office with complaints of fatigue and weakness. Several tests are run revealing a low level of T3, T4. She is diagnosed with hypothyroidism and treated accordingly.

A deficiency of which molecule can also result in underproduction of T3 and T4?

The failure of the glycosylation of proinsulin

A child is being evaluated for possible type 1 diabetes.

Which of the following cellular processes could not result in this insulin dysfunction?

The damaged liver can no longer effectively export cholesterol from the diet in the form of VLDLs and LDLs which is the primary source of steroid hormone precursor

A 66 year old alcoholic man is suffering from severe liver failure. His aldosterone and cortisol levels seem to be getting low.

Why does this disease affect these two hormones?

cortisol

55-year-old male presents to the office with tachycardia and sweating for the past week. He has a history of alcoholic cirrhosis. His blood pressure is 140/90 and his pulse rate is 100 bpm. Serum albumin is 1.8 mg/dL (normal 3.5-4.5 mg/dL).

Which of the following hormones may have increased physiological action due to increased free levels in the serum?

Decreased IGF1

A 13-year-old boy presents for short stature. He was growing appropriately, however 2 years ago his pediatrician noticed he dropped two percentiles on his growth chart. The patient reports he is much smaller than his friends and has not noticed any changes in axillary or pubic hair.

What laboratory test abnormality would you expect to see?

Hyporeflexia

Radiation treatment for a pituitary tumor in an 8-year-old boy results in complete loss of pituitary function.

As a result, the child is likely to experience which of the following symptoms?

Decreased hepatic thyroid-binding globulin synthesis

A 50-year-old male patient presents to a rural clinic complaining of fatigue, constipation, lethargy, and intolerance to cold. Other than being on conservative treatment (low salt diet) for mild hypertension, he has no outstanding history of prior illness or family disease. He is a farmer and consumes a predominantly vegetarian diet, with water derived from a local well. On physical examination, you notice an enlarged mass in the anterior part of his neck, which he has noticed has been slowly growing. His vital signs are: heart rate, 60 beats per minute; blood pressure, 110/70 mm Hg; temperature, 37.8°C (100°F).

Which of the following would you expect to be an underlying mechanism in the pathophysiology in this case?

Increased cAMP formation in the thyroid follicular cell

A radioactive iodine scan revealed greater concentration of radioiodine when compared to that of other asymptomatic individuals. Subsequent laboratory values came back positive for serum titers of thyroid-stimulating immunoglobulin (TSI).

The physiopathology of disease in this patient involves:

prolactin

A 40-year-old truck driver has had difficulty using his side mirrors to see traffic behind him. He has never had any major medical problems in the past. He visits an optometrist, who determines that he has bilateral lateral visual field deficits, but his vision is 20/20. A head computed tomography scan reveals slight enlargement of the sella turcica. He complains of decreased libido for the past 6–9 months.

Which of the following hormones is most likely being secreted in excessive amounts in this man?

E

A hybrid glycoprotein consisting of the α-subunit of follicle-stimulating hormone (FSH) and the β-subunit of thyrotropin (TSH) is injected into a 35-year-old patient at the National Institutes for Health Clinical Research Unit to investigate her endocrine responsiveness.

Which of the following responses is expected following this injection?

	Na+/I− symporter activity	Luteolysis	Thyroglobulin synthesis	Ovulation	T4 release
A	↔	↓	↔	↓	↓
B	↑	↓	↑	↓	↑
C	↑	↔	↓	↔	↔
D	↓	↓	↑	↑	↓
E	↑	↔	↑	↔	↑

B

Laceration of the median eminence during traumatic injury sustained while kickboxing, resulting in the disruption of the hypothalamo-hypophyseal portal circulation would result in which of the following alterations (↑ increase, ↓ decrease, or ↔ no change) in circulating levels of hormones?

	Insulin-like growth factor I	Prolactin	PTH	Growth hormone releasing hormone
A	↔	↑	↓	↔
B	↓	↑	↔	↑
C	↑	↓	↓	↑
D	↑	↔	↔	↓
E	↔	↓	↑	↓

Cyclic guanosine monophosphate (cGMP) in thyroid cells

A group of medical students volunteers for a study in which they are administered injections of TSH over a period of several weeks. They develop weight loss and nervousness. Which of the following would be least affected?

Vasopressin

An endocrine physiologist is studying communication between the hypothalamus and pituitary in a rat model. She interrupts blood flow emanating from the median eminence and then measures circulating levels of pituitary hormones following appropriate physiologic stimulation.

Secretion of which of the following hormones will be unaffected by the experimental manipulation?

Cachexia

During childbirth, a woman suffers a serious hemorrhage and goes into shock. After she recovers, she displays symptoms of hypopituitarism. Which of the following will not be expected in this patient?

growth hormone receptors

A mother brings her 7-year-old son to the pediatrician for an evaluation of his short stature. Blood tests reveal that his average plasma concentration of growth hormone is within the normal range for his age or even slightly elevated, but levels of IGF-I are markedly reduced.

The growth failure in this child is most likely due to a defect in

hypothyroidism due to a primary abnormality in the hypothalamus

A young woman has puffy skin and a hoarse voice. Her plasma TSH concentration is low but increases markedly when she is given TRH.

She probably has:

secondary active transport

In a cell culture model, a scientist transfects mRNA specific for NIS and shows that the transfected cells take up radioactive iodide at a rate that is faster than that seen in control cells.

This increase in intracellular I− due to the action of NIS is an example of

Hyperthyroidism due to circulating antithyroid antibodies with TSH activity

In a 30-year-old female patient being evaluated for a constellation of symptoms suspected to relate to thyroid dysfunction, TRH is infused and the release of TSH is measured. The TSH response to TRH is found to be reduced compared to a normal individual.

Which is the most likely underlying condition?

cholesterol

A 50-year-old woman comes to her physician complaining of unexplained weight gain and memory problems. Physical examination reveals a yellowing of her skin without a discoloration of her sclera. Circulating levels of TSH are increased.

A blood test is likely to reveal increased plasma levels of

Hypernatremia

A 72-year-old woman was in a car accident and hit her head. The force of the trauma severed the pituitary stalk right below the hypothalamus. Which of the following effects is most likely to be seen?

The high affinity of sex hormone binding globulin for estrogen over other androgens

A 55 year old alcoholic man is concerned about his developing breast tissue. He previously had been diagnosed with cirrhosis. Which of the following does not contribute to this gynecomastia?

Tyrosine Kinase

To combat gigantism, a HGH antagonist has been developed. The goal is for it to bind to the HGH receptor and lock the receptor down in people who have excessive HGH. What type of cell signaling mechanism does the receptor the antagonist bind to use?

prolactin

To combat gigantism, a HGH antagonist has been developed. The goal is for it to bind to the HGH receptor and lock the receptor down in people who have excessive HGH. What other hormone uses a similar cell signaling mechanism to the antagonist?

Thyroid hormone is an amine hormone and has a TBG which increases its half life so her levels will remain stable

A frantic 44 year old woman with hypothyroidism calls your office worried sick that she forgot her thyroxine at home. She is on vacation and won’t be able to take it for at least one more day. You assure her that she will be alright and to just take the medicine when she gets home.

Why can you assure her of this?

estrogen

Cancers can secrete many different hormones. Some therapy seeks to block the hormone receptors to prevent paraneoplastic symptoms from occurring.

Which hormone cannot be blocked by an extracellular antibody?

Nitric oxide

A specific genetic defect results in a erroneous guanylate cyclase enzyme. Which hormone’s mechanism of action will be greatly impaired?

GnRH→Anterior Pituitary→FSH/LH→Gonads

Which of the following sequences correctly depicts the order of events following the release of a hypothalamic releasing hormone?

Corticotropes

Of the five types of secreting cells of the anterior pituitary, which of them would be directly affected by the pituitary feedback loop caused by primary adrenal insufficiency?

Increased ACTH/Decreased cortisol

In primary adrenal insufficiency, which of the following findings would be seen on bloodwork?

TRH released from the paraventricular nucleus

A 46 year old woman presents to the clinic with a goiter. She also appears jittery and has bulging eyes. She admits to recent weight loss though no change in diet. After tests, she is diagnosed with Grave’s Disease.

What hormone released from which hypothalamic nucleus can mimic this condition when secreted in large amounts?

ADH

A 45 year old woman presents to the office for generalized fatigue of several years. She has lost weight and eats very little. She cannot tolerate the cold and is generally achey. History reveals she has not has a period since the birth of her third child which was complicated by excessive bleeding.

Which hormone is not affected by the syndrome this woman has?

He will develop diabetes insipidus due to the inability of the posterior pituitary to release ADH

During a traumatic car crash, a 35 year old man suffers damage to his head. An MRI reveals great damage sustained to the posterior pituitary but an intact anterior pituitary.

What can be said about his condition?

Just before waking during REM sleep

A young child of 6 is suspected of having a pheochromocytoma. To confirm this his cortisol level is going to be measured at its lowest point in order to see his baseline concentration.

When would be the best time to test his blood to get this result?

IGF-1 inhibition of GH secretion by binding to the pituitary and hypothalamus

After exercising, a large burst of growth hormone is released into your blood. By what major mechanism is your levels of growth hormone returned to normal levels?

Excessive amounts of GH can activate prolactin receptors due to their similarity

A 10 year old boy who has gigantism presents to your office with a new onset development of breasts. He has never experienced this before as part of his condition. What aspect of GH has led to this symptom development?

Normal GH, low IGF-1

A 18 year old man with extremely short stature presents to your office claiming he has dwarfism. The man has a prominent forehead. He has truncal obesity but is proportione, and blood serum analysis reveals he is hypoglycemic.

Given his most likely condition what would his hormone blood work show?

dopamine

Though both men and women possess breast tissue, neither one lactate constantly. What substance is mainly responsible for the suppression of prolactin?

Adenylyl cyclase

GHRH from the arcuate nucleus and GHIH or somatostatin from the periventricular nucleus bind on different receptors on somatotrophs to control the action of which cell signaling pathway?

goiter

A 35 year old woman is diagnosed with a hormone secreting pituitary tumor. The symptom she complained about which resulted in the finding of the tumor was galactorrhea.

Which of the following symptoms would NOT be associated with her tumor?

The analog will kick endogenous IGF off its globulin reducing its half life and promoting its degradation

An molecule with a very high affinity for the IGFBP is administered to a man suffering from acromegaly to help alleviate the symptoms of his overactive GH.

How might a IGF look alike with an affinity for the globin but not the receptors help reduce the effect of his condition?

V1 receptor in blood vessels causing vasoconstriction via a Gq mechanism

On administering Desmopressin to a healthy male patient, his blood pressure increases.

What receptor and what process are responsible for these findings?

Damage to the supraoptic neurons that make ADH

A 33 year old female presents with complaints of polydipsia and polyuria. She takes no medication, but claims to have suffered a head injury recently. Suspecting a type of diabetes insipidus, a water deprivation test is performed. Her results show the urine does not concentrate, but when given desmopressin, it does.

What is her pathogenesis?

Progesterone and estrogen secreted during pregnancy

A 25 year old pregnant female comes to you complaining of water weight. She is a smoker but claims she stopped when she found out she was pregnant. She claims she feels bloated and full and demands to know why.

In this patient, what is causing her water retention?

The stimulation of the pump promotes oxytocin release which initiating the flow of milk

When trying to collect breast milk for donation, a pump is used to extract the milk from the breast tissue. The pump mimicks the suckling motion of an infant to coax the nipple to release milk.

By what cellular mechanism does this occur?

A change is serum osmolarity sensed by osmoreceptors

ADH is actively regulated by the hypothalamus in the supraoptic nucleus.

Which of the following homeostatic changes would most greatly affect the amount of ADH released by the posterior pituitary?

Neurophysin

A 22 year old girl presents to the office complaining of excessive thirst and excessive urination. Family history reveals that several of her relatives also experienced these symptoms, but are now on medication and are fine.

Given her most likely diagnosis, an a misfolding in what protein is likely causing her symptoms?

positive feedback loop

A 29 year old woman is going into labor. She is administered pitocin to help with contractions.

By what type of feedback mechanism does pitocin exert its effect?

• The thyroid produces more of the less active T4 than T3

• The release of TSH is carefully controlled by the hypothalamus

• Peripheral tissues possess the ability to de-iodinate T4 to T3 as needed

• T3 can be inactivated into rT3 which prevents its biological action

In order to carefully control the amount of T3 present in the body, there are several systems in place to regulate this substance.

Which ways do the body try to control the action and release of T3?

Excess exogenous TH suppresses the hypothalamic-pituitary axis resulting in major suppression of endogenous TH production

A newly diagnosed hypothyroid patient is discussing with you, her doctor, the medication she will be on levothyroxine. You tell her one of the side effects is weight loss. She asks why don’t you prescribe it for obese patients then.

How would exogenous T3 affect the homeostasis of a healthy person?

Euthyroid Sick Syndrome

A 77 year old man is rushed to the hospital after having an MI. The stress of the surgery to save him has made him acutely ill with a staph infection. A gamut of tests is run on the clinically ill man and it shows the following with reference to his thyroid:

T4 normal, T3 low, rT3 increased, rT3 increased, TSH normal

What other condition is this man suffering from?

LOW TSH, HIGH T3/4

A 45 year old man presents to the office with weight loss, heat intolerance, and the jitters. He claims his diet hasn't changed. His neck looks slightly swollen. A serum blood test reveals the presence of TSHR autoantibodies.

Given this information, what would his blood work looks like?

The thyroid receptor is a nuclear receptor and binds to a thyroid response element to induce transcription

T4 and T3 are secreted by the thyroid gland into circulation upon TSH stimulation. T3 and T4 have a wide range of varying actions throughout the body.

Which of the following is true regarding the mode of action of TH?

TPO (thyroid peroxidase)

While working at a clinic in Ghana, a 23 year old woman presents to you with a goiter. You determine after a physical exam and some tests, that she is iodine deficient and consequently has hypothyroidism.

Which enzyme or protein s activity is greatly altered due to the lack of iodine in the patient’s diet and resulted in her goiter?

A.hCG from the placenta can cross react with the TSH receptor due to its homology with TSH

A newly pregnant mother presents to the office for a first wellness visit. A gamut of tests is run on the woman and it is revealed she has an elevated TH. She seems concerned but you tell her not to worry. By what mechanism does this occur?

Decrease in erythropoietin production

The thyroid possess the ability to self regulate itself under the Wolff-Chaikoff effect.

What would one expect to find in examining a person who has been given several large boluses of iodine?

A drug that inhibits the Gi subunit of the TSHR

A new medication seeks to treat TSH secreting tumors by interfering with the TSH receptor on thyroid follicular cells.

Which one of these cellular mechanism would NOT work on interfering with TSH signaling?

vasopressin relieves her sx

A 25-year-old female with no significant past medical history presents to her gynecologist with a complaint of intense thirst and an increased frequency of urination. She states that her mouth always feels dry, despite drinking a significant amount of water. Her urine is clear. She denies a change in appetite. The patient had suffered significant head trauma after involvement in a motor vehicle accident 2 months ago. A CT of the brain at that time was remarkable for a cerebral contusion without evidence of bleeding. Besides a mild, persistent headache, she feels like she is at baseline cognitively. Vital signs reveal:

Temperature	36.7°C (98.1°F)
Blood pressure	110/73 mmHg
Heart rate	74/min
Respiratory rate	12/min
Oxygen saturation	98% on room air

Physical examination is unrevealing. Laboratory studies reveal a urine specific gravity of 1.002 (reference range: 1.005-1.030) and serum sodium of 149 mEq/L (reference range: 136-145 mEq/L).

The most likely additional finding is:

lungs

A 75-year-old man with a 45 pack-year smoking history presents to the emergency department with confusion. He has no significant medical history and has not seen a physician for almost 30 years, but his wife thinks he has lost some weight in the past few months. Vital signs are normal. Laboratory studies reveal a serum sodium of 127 mEq/L (reference range: 136–145 mEq/L).

The current presentation is most likely due to the pathologic production of a substance in the

ligand-receptor cross-reactivity between β-hCG and TSH

A 23-year-old man with nonseminomatous testicular cancer is referred to an endocrinologist because he has been experiencing sweating, diarrhea, and a sensation that his heart is racing. He denies other symptoms, including weight loss. He is currently on bleomycin for treatment of his cancer.

The most likely pathophysiologic mechanism of this patient's symptoms is

proptosis and pretibial myxedema

A 46-year-old female presents to her primary care physician with the complaint of proximal muscle weakness that has progressively worsened over the past 3 months. She states it has become more difficult to comb her hair, as well as walk up stairs. She admits to deconditioning from a sedentary lifestyle and obesity. Despite this, she has lost approximately 10 lbs (4.5 kg). She has no previous medical history and takes no current medications. She has a 45-pack-year smoking history. Vital signs reveal:

Temperature	37.2°C (98.9°F)
Blood pressure	130/79 mmHg
Heart rate	104/min

The patient has a body mass index of 38. Physical exam reveals persistent 4/5 strength in thighs and shoulder abduction, with range of motion limited by weakness only, and 3+ deep tendon reflexes are present. A recent cholesterol panel revealed low-density lipoproteins of 38 mg/dL (reference range: < 130 mg/dL); a complete blood count is normal.

Given the most likely diagnosis, which of the following would be expected in this patient?

atrophy

A 60-year-old female presents to her primary care physician having experienced a variety of thyroid and anterior pituitary-related symptoms for the past year, including anxiety, weight loss, and diarrhea. She has also recently been experiencing visual symptoms consistent with bitemporal hemianopsia. Imaging of the brain shows a pituitary macroadenoma encroaching on the optic chiasm. A transsphenoidal approach to resect the anterior pituitary gland is successful.

Biopsy of this patient's thyroid gland several years after the pituitary resection would most likely show:

hydrochlorothiazide

A 41-year-old male presents to the office with complaints of polydipsia and polyuria. In addition, he states that he wakes up 2-3 times nightly to urinate, which has caused him to feel fatigued during the day. He estimates his urine output to be "1 gallon." He denies dysuria or incontinence and states that the urine is clear. He feels thirsty all the time and feels like he is drinking excess amounts of water. He has no previous medical history and denies tobacco or alcohol use. Vital signs and physical examination are unremarkable. Laboratory analysis reveals a serum sodium level of 145 mg/dL (reference range: 136-145 mg/dL) with urine osmolality 320 mOsm/L (reference range: 50-1200 mOsm/L). He undergoes a water restriction test and 3 hours later his serum sodium is 149 mg/dL with unchanged urine osmolality. Desmopressin is administered with no change to his serum sodium level and an increase of 5% of his urine osmolality.

The most appropriate treatment is

stage 3/4 is the most replenishing for the infant because the greatest amount of growth hormone is released at this time

A 30-year-old female gave birth to a healthy baby girl. The first-time mother is concerned that her daughter is sleeping 18 hours-a-day. The physician eases her concerns by explaining why her daughter is sleeping for so many hours.

Which of the statements regarding sleep cycles did the physician most likely use?

RET

A 32-year-old female presents to the emergency department with the complaints of headache, palpitations, and diaphoresis for the past 2 hours. She has been seen 3 times in the last 5 months for similar symptoms. Vital signs reveal:

Temperature	37.4°C (99.4°F)
Blood pressure	155/95 mmHg
Heart rate	108/min
Respiratory rate	14/min

The patient has clear breath sounds bilaterally and no murmurs are heard during cardiac auscultation. Her deep tendon reflexes are 2+ bilaterally. Serum laboratory studies reveal thyroid-stimulating hormone is 3.2 μU/mL (0.4-4.2 µU/mL) and calcitonin is 47.6 mg/dL (≤ 14 pg/mL). CT of the abdomen shows a mass in the left adrenal gland.

This patient most likely has a mutation in which of the following genes?

negative free-water clearance

A 60-year-old female presents to the office with a chronic cough, fatigue, and unintentional weight loss. She also states that she occasionally sees blood in her sputum. She has a 40-pack-year smoking history. Vital signs reveal:

Temperature	37.1°C (98.8°F)
Blood pressure	135/85 mmHg
Heart rate	81/min
Respiratory rate	16/min
Oxygen saturation	91%

She has moist mucous membranes and a positive axillary sweat test; there is no peripheral edema. Chest auscultation is remarkable for diffuse wheezes. Her blood work is notable for a serum sodium of 120 mEq/L (reference range: 136-145 mEq/L). CT scan of the chest is obtained as shown in the exhibit.

Additional examination is most likely to reveal

lactotroph

A 63-year-old female is involved in a minor motor vehicle accident and is brought into the emergency department for evaluation. She states she went to change lanes and did not see the car beside her. She has had 2 other near collisions prior to this under similar circumstances. She has a history of asthma and chronic back pain, headaches, as well as a prior cervical fusion surgery 2 years ago. Vital signs reveal:

Temperature	36.8°C (98.2°F)
Blood pressure	112/74 mmHg
Heart rate	94/min
Respiratory rate	18/min

The patient is alert and oriented to person, place, time, and situation. Neurologic examination reveals pupils that are 4 mm in diameter and reactive, intact extraocular movements, and markedly decreased peripheral vision bilaterally. Motor strength is 5/5 in the upper and lower extremities bilaterally, with patellar and brachioradialis deep tendon reflexes graded as 2/4 bilaterally. Osteopathic examination reveals tenderness in the lumbar paraspinal muscles, and the associated segments are pulled into a group curve dynamic. The remainder of the physical examination is within normal limits.

Hyperplasia of which cell type is most likely in this patient?

regulate sleep–wake cycles

An 11-year-old male is brought to the office by his parents because of insomnia for the last 6 weeks. He has recently began to experience regular headaches and says that they are sometimes accompanied by nausea and vomiting. Physical examination reveals a downward gaze, and the patient is unable to look up when asked to do so. Brain imaging reveals a solitary tumor.

This patient's tumor most likely originated from a structure that functions to

serum prolactin level

A 37-year-old female presents to the office with depression and fatigue. She states that she just doesn't have the same amount of energy that she used to and has now noticed a weight gain of 12 pounds during the past 2 months. She denies suicidal ideation. Further questioning reveals cold intolerance and constipation. Her menstrual cycles are irregular, but she denies sexual activity. She has no previous medical history and takes no medication. Vital signs reveal a heart rate of 55/min. Physical examination reveals dry skin and hypopigmentation. There is mild thyroid enlargement but no palpable nodules and no tenderness. Laboratory studies reveal a thyroid-stimulating hormone level of 18.9 mU/mL (reference range: 0.4–4.2 mU/mL).

Which of the following would most likely be increased?

Hashimoto thyroiditis

A 45-year-old female presents to the office with a 2-week history of anxiety, palpitations, and night sweats. She has not noticed any change in weight but does report an enlarging area on her neck. She denies any other medical history and takes no medications or supplements except a daily vitamin. She drinks alcohol occasionally and quit smoking 6 years ago. Vital signs reveal:

Temperature 36.8°C (98.2°F)

Blood pressure 136/82 mmHg

Heart rate 98/min

Respiratory rate 12/min

Oxygen saturation 99% on room air

Physical examination reveals a diffusely enlarged thyroid that is nontender. Laboratory studies reveal a thyroid-stimulating hormone level of 0.3 mU/L (reference range: 0.4–4.2 mU/L) with positive anti-thyroid peroxidase antibodies. A fine-needle aspiration biopsy is obtained, and the findings are shown in the exhibit.

The most likely diagnosis is

complement activation by antibodies bound to thyroid epithelial cells

A 32-year-old female presents to the office with fatigue and recent weight gain. She also reports experiencing difficulty focusing at work. Physical examination reveals bradycardia and delayed reflexes. Laboratory studies reveal low levels of thyroid hormones. The most likely cause of this patient's symptoms is

TSH

A 30-year-old male presents for consultation from an endocrinologist after a recent magnetic resonance imaging of the brain revealed a suprasellar adenoma. The brain imaging was initially ordered due to new-onset migraines. No other abnormalities were seen. In addition, the patient has recently been seen in the emergency department for complaints of a fast heart rate and anxiety attacks. Physical exam reveals a diffusely enlarged thyroid gland.

Which of the following would differentiate Graves' disease from this patient's most likely diagnosis?

growth hormone

A 58-year-old male presents to the office after being seen in the emergency department for a humeral neck fracture sustained while lifting a heavy box. His arm is in a cast, and he has a follow-up appointment with an orthopedic surgeon. He has a history of nasopharyngeal carcinoma, for which he received radiation therapy 2 years ago. He is now in remission but has noticed some muscle wasting, as well as less energy than friends of the same age. He takes levothyroxine for central hypothyroidism, and his T4 level is within the appropriate range. Other laboratory studies reveal hyperlipidemia.

The most likely primary dysfunction is a deficiency of

exogenous hyperthyroidism (from taking his mom’a pills)

A 19-year-old male presents to his primary care physician with complaints of heat intolerance, anxiety, and palpitations. He has a family history of thyroid disease; his mother is on daily thyroid hormone replacement therapy. He lives with his mother while attending college on a wrestling scholarship. He says his academics have declined recently because he is stressed about maintaining a low weight for wrestling. Vital signs show a blood pressure of 124/90 mmHg, a heart rate of 128/min, a respiratory rate of 17/min, and a BMI of 18 kg/m². Physical examination reveals a thin-appearing male with a mild hand tremor. Auscultation of the heart reveals tachycardia with an irregularly irregular rhythm. No thyroid enlargement or tenderness is noted. Labs reveal a TSH of < 0.01 mU/L (reference range 0.4–4.2 mU/L) with an elevated T4. EKG displays atrial fibrillation. A thyroid scan is obtained and shows an absence of uptake.

The most likely diagnosis is

TRH

A 31 year-old pregnant female in her first trimester is being evaluated by her obstetrician due to complaints of increased anxiety, weight loss and a "funny feeling in my chest" for the past 3 months. In addition, she feels like she is always warm, and despite being pregnant, has lost 4 lbs (1.8 kg). She denies taking excess caffeine, and is only taking a prenatal vitamin. Vital signs reveal a heart rate of 102/min. Thyromegaly without nodules is present. A recent noncontrasted CT of the head was completed 2 weeks ago after a motor vehicle injury that revealed a suprasellar adenoma, but was without hemorrhage.

Given these findings, which of the following is most likely to be suppressed in this patient?

anterior pituitary gland

A 35-year-old female presents to the office with headaches. They are intermittent but have been worsening for the past year. She denies weakness, nausea, vomiting, tremors, or seizure-like activity. Review of symptoms reveals oligomenorrhea for at least 10 years. Vital signs are within normal limits. Physical examination reveals macroglossia and macrognathia. The hormone responsible for this presentation is produced in the

IGF-1

A 44-year-old female presents to the office for her annual physical. She states she is doing well but reports progressively worsening pain in the joints of her fingers bilaterally. She believes her wedding ring fits much tighter than before. She also states her husband told her she has been snoring over the past 6 months. Vital signs reveal no abnormalities. Physical examination reveals she has grown 1 inch in the past year. Carpal joints are examined bilaterally and found to be mildly enlarged, compared to last year's physical examination. Diagnostic studies reveal a hemoglobin A1c of 6.2% (reference range: 4.2–5.9%).

Which of the following laboratory tests would be most useful for determining the diagnosis?

Primary disorder of the thyroid gland

A 42-year-old woman presents with fatigue, cold intolerance, and constipation. Lab testing shows low T4 and elevated TSH.

Which classification best describes this endocrine disorder?

Ovarian tumor secretion of hCG stimulating TSH receptors

A 28-year-old woman presents with palpitations, weight loss, and heat intolerance. On exam, she has tachycardia and a diffuse goiter. Laboratory studies reveal elevated free T4 and suppressed TSH. A pregnancy test is negative. Imaging shows a large ovarian mass.

Her symptoms are most likely explained by which of the following mechanisms?

Decreases the free fraction of testosterone, reducing its bioavailability

A 54-year-old man with a history of hepatitis C and cirrhosis presents with new-onset gynecomastia. Labs show elevated sex hormone-binding globulin (SHBG).

Which of the following best explains the effect of increased SHBG on circulating sex hormones?

Thyroid hormone permissively increases the number of β-adrenergic receptors in cardiac tissue

A 32-year-old woman is started on high-dose thyroid hormone replacement after thyroidectomy. During follow-up, she reports new-onset palpitations and anxiety. Vital signs reveal tachycardia and elevated blood pressure.

Which of the following best explains how thyroid hormone contributes to her cardiovascular symptoms?

Pituitary dysfunction leading to loss of TSH secretion (secondary hypothyroidism)

A 42-year-old man presents with fatigue, weight gain, and constipation. Laboratory studies show:

TSH: Low

Free T4: Low

Which of the following best explains these findings?

Secondary pituitary failure due to ischemic necrosis

A 33-year-old woman presents with fatigue, cold intolerance, and amenorrhea. She reports she was unable to breastfeed after her last delivery, which was complicated by massive postpartum hemorrhage. Lab results show:

●TSH: low-normal

●Free T4: low

●ACTH: low

●Cortisol: low

●Prolactin: low

Which of the following best explains her condition?

Pulsatile release, with the largest peaks occurring shortly after sleep onset during slow-wave sleep

A 19-year-old male undergoes a sleep study. His growth hormone (GH) secretion pattern is analyzed.

Which of the following best describes the expected physiologic release?

TSH

Which of the following hormones originates in the anterior pituitary?

Thyrotropin-releasing hormone (TRH); stimulates both thyrotrophs and lactotrophs

A 30-year-old woman presents with fatigue, weight gain, constipation, and irregular menses. She also reports milky breast discharge despite not being pregnant. Physical exam confirms galactorrhea. MRI of the brain shows no mass.

Which of the following is most likely responsible for her findings, and what is unique about its action?

Synthesized in the hypothalamus; stored in posterior pituitary axon terminals until systemic release

A 48-year-old man with a history of traumatic brain injury presents with excessive thirst and frequent urination. Labs reveal:

●Serum sodium: 152 mEq/L

●Urine osmolality: 90 mOsm/kg

A water deprivation test fails to concentrate his urine, but administration of desmopressin normalizes it.

Which of the following best describes the hormone affected in this patient?

hypothalamic nuclei

A 58-year-old man is brought by his wife to the emergency department with a 3-day history of progressive confusion and frequent urination. She notes that the patient has been drinking excessive amounts of water and waking up multiple times overnight to urinate. Medical history reveals a pituitary macroadenoma, which was resected 2 months ago. Medications include levothyroxine and hydrocortisone. Vital signs reveal:Temperature 37.0°C (98.6°F) Blood pressure 100/62 mmHg Heart rate 98/min Respiratory rate 16/min Oxygen saturation 98% on room airThe patient appears lethargic but is oriented to person. Physical examination reveals dry mucous membranes. Neurologic examination reveals no focal deficits. Laboratory studies reveal: high serum sodium, high serum osmolality, and low urine osmolality

An MRI of the brain reveals postoperative changes in the sella turcica, without residual tumor.

The hormones that are deficient in this patient’s condition are synthesized in which of the following locations?

adequate energy and protein intake and consistently getting a full night’s rest are required to produce optimal amounts of growth hormone

A tired-appearing 15-year-old male is brought to your office by his 6’6” tall biological father. The patient is frustrated because he had aspirations of playing college basketball like his father, but he does not seem to be growing as expected. He was the tallest student in his class until 6th grade year when he joined the wrestling team, at which point he started limiting how much he’d eat and partaking in periodic fasts to be able to make competition weight. He is now in the bottom 10% of his male classmates in regard to height. He still participates in wrestling and the weight-cutting activities. He has also developed the habit of staying up until 2-3 am on school nights to play video games.

Having a sound understanding of requirements for proper growth hormone production, you tell him: 

gonadotropes

A 3-year-old boy is brought to your clinic by his mother who reports that he fell under 5% for stature (height) for age on his recent growth chart. Gene sequencing is carried out and a mutation in the Pit-1 gene found.

Which of the following cells do you expect to be normal with a mutated Pit-1 gene and a normal Prop-1 gene?

jak/stat pathway

When growth hormone (GH) binds to the GH receptor, the signaling pathway that is activated is the:

cardiomegaly and hyperglycemia 

A 36 year-old woman who is a fitness enthusiast comes in complaining of being thirsty all the time despite drinking water seemingly constantly, and having to urinate frequently. She is also experiencing some mild shortness of breath and feels her heart thumping in her chest at times. Upon questioning the patient, she tells you she has been injecting herself with growth hormone for 3 years to aid in recovery and as an anti-aging modality. You order a chest x-ray, a CMP, and a CBC.

What do you expect to see?

gigantism; octreotide

A 13-year-old male patient presents with abnormally tall stature, hyperglycemia, and gynecomastia. You check his GH and IGF-1 levels and they are far in excess of the normal range.

You diagnose him with _______ and treat him with _______.

they increase

When osmoreceptor cells decrease in size, what happens to ADH levels?

very low levels of oxytocin

A 15-year-old female falls and hits her head during a volleyball game. She suffers a concussion and proceeds to have ongoing symptoms for weeks. She enters into a study at a local university looking at a new imaging modality that can localize dysfunction in injured brains. It’s found that her paraventricular nucleus is damaged and completely non-functional.

What effect do you expect to see on her levels of posterior pituitary hormone production?

central

A 6 year-old boy is brought to your clinic by his mom because he’s been urinating frequently and drinking copious amounts of water. He has a history of TBI, so in addition to a urinalysis and genetic test, you order an MRI of his brain. The MRI shows a lack of the posterior pituitary bright spot that should be present, and his urine osmolarity is very low. The genetic test reveals a mutation in the AVP-NPII gene. You give him desmopressin and he improves.

What type of diabetes insipidus is this?

blood pressure, because oxytocin is similar in structure to ADH and can overlap with its actions

A first year OB-GYN resident miscalculates the dose of synthetic oxytocin (ptocin) to use to give to her patient for labor induction. She gives the patient 2 times the amount needed along with a bolus of free water.

What vital sign should be monitored very closely and why?

progestins decrease the response of the uterine myometrium to oxytocin which could hinder contractions

You’re an OB-GYN and a patient that is transferring to you from another OB physician at the 8 month of pregnancy is at your clinic complaining of morning sickness. Upon extensive chart-review and patient interview, it is revealed that her pregnancy was a surprise, as she had a progestin implant as birth control. It is also revealed that the implant was never removed.

Why is this a concern going forward?

TRH

A 31 year-old pregnant female in her first trimester is being evaluated by her obstetrician due to complaints of increased anxiety, weight loss and a "funny feeling in my chest" for the past 3 months. In addition, she feels like she is always warm, and despite being pregnant, has lost 4 lbs (1.8 kg). She denies taking excess caffeine, and is only taking a prenatal vitamin. Vital signs reveal a heart rate of 102/min. Thyromegaly without nodules is present. A recent noncontrasted CT of the head was completed 2 weeks ago after a motor vehicle injury that revealed a suprasellar adenoma, but was without hemorrhage.

Given these findings, which of the following is most likely to be suppressed in this patient?