Endocrine

Which hormones are secreted by anterior pituitary basophils?

ACTH, TSH, FSH, LH

Which hormones are secreted by anterior pituitary acidophils?

GH and prolactin

Which hypothalamic hormones stimulate anterior pituitary secretion?

CRH → ACTH; TRH → TSH and prolactin; GnRH → FSH and LH; GHRH → GH

Which hypothalamic hormones inhibit anterior pituitary secretion?

Dopamine inhibits prolactin; somatostatin inhibits GH and TSH

What is the effect of pulsatile versus continuous GnRH?

Pulsatile GnRH stimulates FSH/LH; continuous GnRH suppresses them

Which hormones act through the cAMP signaling pathway?

FSH, LH, ACTH, TSH, CRH, hCG, ADH (V2), MSH, PTH, glucagon

Which hormones act through IP3/DAG signaling?

GnRH, TRH, oxytocin, ADH (V1), angiotensin II

Which hormones act through receptor tyrosine kinase?

Insulin and IGF-1

What stimulates GH secretion, and what inhibits it?

Stimulated by GHRH, sleep, hypoglycemia, stress, puberty, exercise; inhibited by somatostatin

What are the major effects of GH?

Stimulates IGF-1 production, linear growth, muscle mass, and insulin resistance

What causes elevated prolactin, and what are its effects?

Dopamine antagonists or hypothyroidism; causes galactorrhea, amenorrhea, infertility, and hypogonadism

What is the first-line medical treatment for prolactinoma?

Dopamine agonists: cabergoline or bromocriptine

What stimulates ADH release?

Increased plasma osmolality and decreased blood volume

What are the actions of ADH at V1 versus V2 receptors?

V1: vasoconstriction; V2: aquaporin insertion → increased water reabsorption

How does central diabetes insipidus differ from nephrogenic diabetes insipidus?

Central: deficient ADH; nephrogenic: renal resistance to ADH

How does urine respond to desmopressin in central versus nephrogenic DI?

Central DI: urine osmolality increases; nephrogenic DI: minimal response

What characterizes SIADH laboratory findings?

Hyponatremia, low serum osmolality, concentrated urine, increased urine sodium

What are the major effects of cortisol?

Increases gluconeogenesis and blood pressure; decreases inflammation, immunity, collagen synthesis, and bone formation

Which adrenal cortical zones produce aldosterone, cortisol, and androgens?

Glomerulosa: aldosterone; fasciculata: cortisol; reticularis: androgens

What regulates aldosterone secretion?

Angiotensin II and increased serum potassium; ACTH has a minor role

What are the characteristic findings of primary adrenal insufficiency?

Low cortisol, high ACTH, hyperpigmentation, hypotension, hyponatremia, hyperkalemia

What distinguishes primary from secondary adrenal insufficiency?

Primary: low cortisol, high ACTH, often low aldosterone; secondary: low cortisol, low ACTH, aldosterone usually preserved

What causes Cushing syndrome?

Excess glucocorticoids from exogenous steroids, adrenal tumors, pituitary ACTH, or ectopic ACTH

How does Cushing disease differ from Cushing syndrome?

Cushing disease specifically refers to an ACTH-secreting pituitary adenoma

What are typical features of Cushing syndrome?

Central obesity, moon facies, buffalo hump, purple striae, hypertension, hyperglycemia, muscle weakness

What is the typical laboratory pattern in primary hyperaldosteronism?

Increased aldosterone, decreased renin, hypertension, hypokalemia, metabolic alkalosis

What is the typical laboratory pattern in secondary hyperaldosteronism?

Increased aldosterone and increased renin

What are the three major enzyme deficiencies causing congenital adrenal hyperplasia?

21-hydroxylase, 11β-hydroxylase, and 17α-hydroxylase deficiencies

What are the characteristic findings of 21-hydroxylase deficiency?

Decreased cortisol and aldosterone, increased androgens, increased 17-hydroxyprogesterone

What are the characteristic findings of 11β-hydroxylase deficiency?

Decreased cortisol, increased androgens and deoxycorticosterone → hypertension and hypokalemia

What are the characteristic findings of 17α-hydroxylase deficiency?

Decreased cortisol and sex steroids, increased mineralocorticoid activity → hypertension, hypokalemia, sexual infantilism

What is the classic presentation of pheochromocytoma?

Episodic headache, sweating, palpitations, and hypertension

Which laboratory tests are used to screen for pheochromocytoma?

Plasma free metanephrines or 24-hour urinary fractionated metanephrines

What is the correct treatment sequence before pheochromocytoma surgery?

Alpha blockade first, then beta blockade if needed

What are the characteristic features of Graves disease?

TSH-receptor stimulating antibodies, diffuse goiter, hyperthyroidism, ophthalmopathy, pretibial myxedema

What are the characteristic antibodies and histology of Hashimoto thyroiditis?

Anti-TPO and anti-thyroglobulin antibodies; Hürthle cells and lymphoid germinal centers

What is the typical thyroid function pattern in primary hypothyroidism?

Increased TSH and decreased free T4

What is the typical thyroid function pattern in primary hyperthyroidism?

Decreased TSH and increased free T3/T4

What characterizes subacute granulomatous (de Quervain) thyroiditis?

Postviral, painful tender thyroid, increased ESR, transient hyperthyroidism

What is the typical progression of postpartum thyroiditis?

Transient hyperthyroidism → hypothyroidism → recovery

What are the characteristic findings of papillary thyroid carcinoma?

Most common thyroid cancer; Orphan Annie nuclei, nuclear grooves, psammoma bodies, lymphatic spread

How does follicular thyroid carcinoma spread, and what distinguishes it from adenoma?

Hematogenous spread; capsular or vascular invasion distinguishes carcinoma from adenoma

What are the characteristic features of medullary thyroid carcinoma?

Parafollicular C-cell origin, calcitonin secretion, amyloid stroma, association with MEN2

What are the characteristic features of anaplastic thyroid carcinoma?

Older patient, rapidly enlarging neck mass, compressive symptoms, very poor prognosis

What are the characteristic findings of primary hyperparathyroidism?

Increased PTH and calcium; decreased phosphate; commonly due to adenoma

What causes secondary hyperparathyroidism?

Chronic hypocalcemic stimulus, commonly vitamin D deficiency or chronic kidney disease

What causes tertiary hyperparathyroidism?

Autonomous PTH secretion after prolonged secondary hyperparathyroidism, typically in chronic kidney disease

What are the typical findings in hypoparathyroidism?

Decreased PTH and calcium, increased phosphate; may cause tetany

What are Chvostek and Trousseau signs?

Chvostek: facial twitch after tapping facial nerve; Trousseau: carpal spasm after BP cuff inflation

What characterizes pseudohypoparathyroidism type 1A?

GNAS mutation causing PTH resistance; increased PTH, decreased calcium, increased phosphate, Albright hereditary osteodystrophy

What are the characteristic features of vitamin D deficiency?

Decreased calcium and phosphate, increased PTH; rickets in children and osteomalacia in adults

What is the main action of calcitonin?

Secreted by thyroid C cells; inhibits osteoclast activity and lowers serum calcium

What are the characteristic features of type 1 diabetes mellitus?

Autoimmune β-cell destruction, absolute insulin deficiency, associated with HLA-DR3/DR4

What are the characteristic features of type 2 diabetes mellitus?

Insulin resistance with progressive β-cell dysfunction; associated with obesity and metabolic syndrome

What distinguishes DKA from HHS?

DKA: ketones and metabolic acidosis, usually type 1; HHS: severe hyperglycemia and hyperosmolality with minimal ketosis

What are the major chronic complications of diabetes mellitus?

Retinopathy, nephropathy, neuropathy, macrovascular disease

Which pancreatic cells secrete insulin, glucagon, and somatostatin?

Beta cells: insulin; alpha cells: glucagon; delta cells: somatostatin

What are the characteristic features of insulinoma?

Hypoglycemia with increased insulin, C-peptide, and proinsulin

What are the characteristic features of glucagonoma?

Diabetes, weight loss, and necrolytic migratory erythema

What are the characteristic features of somatostatinoma?

Diabetes, gallstones, steatorrhea, and hypochlorhydria

What are the characteristic features of MEN1?

Parathyroid, pancreatic endocrine, and pituitary tumors

What are the characteristic features of MEN2A?

Medullary thyroid carcinoma, pheochromocytoma, and parathyroid hyperplasia

What are the characteristic features of MEN2B?

Medullary thyroid carcinoma, pheochromocytoma, mucosal neuromas, and marfanoid habitus