Endocrinology and Metabolism
Core framework
Approach endocrine problems with dynamic testing logic: establish whether a hormone axis is under- or overactive, then localise the lesion. For diabetes, know the diagnostic thresholds, the difference between type 1 and type 2 presentations, and the acute emergencies (diabetic ketoacidosis and hyperosmolar hyperglycaemic state) with their fluid, insulin and potassium protocols.
Concepts examiners test
Thyroid: primary versus secondary hypothyroidism, subclinical disease, Graves versus toxic multinodular disease, thyroid storm recognition and treatment order, and amiodarone effects. Adrenal: primary versus secondary insufficiency, cosyntropin testing, adrenal crisis management, and Conn syndrome screening. Pituitary: prolactinoma, acromegaly screening with IGF-1 and glucose suppression, and hypopituitarism. Calcium: primary hyperparathyroidism versus malignancy, and the emergency of severe hypercalcaemia. Also know osteoporosis management and diabetic foot assessment.
Traps
- Thyroid storm treatment order matters: beta-blocker, thionamide, then iodine after the thionamide; supportive care throughout.
- Do not start levothyroxine before excluding adrenal insufficiency in a patient with suspected hypopituitarism - it can precipitate adrenal crisis.
- DKA potassium can be normal or high despite total body depletion; check and replace before insulin if low.
- Insulin is not the initial treatment in hyperosmolar hyperglycaemic state until fluids are given.
- Corrected calcium is needed when albumin is abnormal.
Worked rule of thumb
A patient with known autoimmune disease presents with hypotension, hyponatraemia and hyperkalaemia: suspect primary adrenal insufficiency; draw cortisol and ACTH, then give hydrocortisone and fluids immediately without waiting for results.