Chapter 3 of 156% of exam

Endocrine System

Endocrine questions test hormone physiology through its failures: excess, deficiency and tumors. The blueprint covers adrenal, pituitary, thyroid and parathyroid disease, diabetes, hypogonadism, metabolic syndrome and endocrine neoplasia.

Thyroid and parathyroid

Thyroid disorders are interpreted from TSH and free T4 together, and the physical findings often name the cause. Treatment choices depend on age and cardiac status. Primary hyperparathyroidism is most often a single adenoma.

Graves disease

Hyperthyroidism with a diffuse goiter, exophthalmos or infiltrative dermopathy; the most common cause of hyperthyroidism.

Merck Manual Professional Edition, Hyperthyroidism

Starting levothyroxine

Older patients and those with heart disease start at a low dose (for example 25 mcg) with adjustments about every 6 weeks.

Merck Manual Professional Edition, Hypothyroidism

Primary hyperparathyroidism

The most common cause is a solitary parathyroid adenoma.

Merck Manual Professional Edition, Hyperparathyroidism

Adrenal disorders

Adrenal questions ask you to pick the right screening test and avoid dangerous treatment sequences. Screening tests for excess and deficiency are different. Pheochromocytoma has a specific preoperative drug order.

Addison disease

Hyperpigmentation, hyponatremia and hyperkalemia; confirmed with serum cortisol, plasma ACTH and ACTH (cosyntropin) stimulation testing.

Merck Manual Professional Edition, Primary Adrenal Insufficiency

Cushing syndrome screening

Late-night salivary cortisol, 24-hour urinary free cortisol, or a dexamethasone suppression test establish cortisol excess before ACTH localizes the cause.

Merck Manual Professional Edition, Cushing Syndrome

Pheochromocytoma

Screen with plasma free or urinary metanephrines; start alpha-blockade before any beta-blocker to avoid unopposed alpha stimulation.

Merck Manual Professional Edition, Pheochromocytoma

Diabetes and pituitary

Diabetic emergencies are managed in a fixed priority order: restore volume, protect potassium, then give insulin. Pituitary tumors are classified by the hormone they secrete or by mass effect. Prolactinomas are usually treated medically before surgery is considered. Thyroid nodules are common, and ultrasound decides which need sampling.

DKA priorities

Give IV 0.9% saline, correct hypokalemia, and start IV insulin only when potassium is at least 3.3 mEq/L.

Merck Manual Professional Edition, Acute Complications of Diabetes Mellitus

Prolactinoma

A dopamine agonist is the usual initial treatment, and cabergoline is preferred because it is better tolerated.

Merck Manual Professional Edition, Prolactinoma

Thyroid nodules

Ultrasound features and size decide whether fine-needle aspiration is needed.

Merck Manual Professional Edition, Approach to the Patient With a Thyroid Nodule

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