Endocrine

Hypothalamic-pituitary axes, thyroid, adrenal and diabetes with feedback-loop reasoning.

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Pituitary

Prolactinoma: amenorrhea, galactorrhea, low libido; treat with cabergoline or bromocriptine before surgery.
Acromegaly: elevated IGF-1 is the screening test, confirm with failure of GH suppression on oral glucose; treat with surgery then octreotide.
Sheehan syndrome: postpartum pituitary infarction — failure to lactate then other axis failures.
Central diabetes insipidus responds to desmopressin; nephrogenic does not — lithium and hypercalcemia are common causes.

Graves disease: TSI antibodies, diffuse goiter, exophthalmos and pretibial myxedema from fibroblast stimulation.
Hashimoto thyroiditis: anti-TPO, Hürthle cells and germinal centers, risk of thyroid lymphoma.
Subacute (de Quervain) thyroiditis follows a viral illness with a painful gland and raised ESR — self-limited.
Papillary carcinoma is the most common with Orphan Annie nuclei and psammoma bodies; medullary secretes calcitonin and appears in MEN2.

Cushing syndrome workup: confirm with late-night salivary cortisol or dexamethasone suppression, then use ACTH to localise.
Primary adrenal insufficiency has hyperpigmentation and hyperkalemia; secondary does not (aldosterone is preserved).
Conn syndrome: hypertension with hypokalemia and metabolic alkalosis; high aldosterone-to-renin ratio.
Pheochromocytoma: episodic headache, sweating, palpitations; plasma metanephrines, α-blockade with phenoxybenzamine before β-blockade.

Diagnose diabetes with HbA1c ≥ 6.5%, fasting glucose ≥ 126, 2-hour OGTT ≥ 200, or random ≥ 200 with symptoms.
DKA occurs in type 1 with ketones and anion-gap acidosis; hyperosmolar hyperglycemic state in type 2 without significant ketosis.
Metformin is first line — lactic acidosis risk in renal failure; SGLT2 inhibitors cause genital mycotic infection and euglycemic DKA.
MEN1: parathyroid, pituitary, pancreas; MEN2A: medullary thyroid, pheochromocytoma, parathyroid; MEN2B swaps parathyroid for mucosal neuromas.