Endocrinology, Diabetes, and Metabolism
The endocrine block mixes emergencies (DKA, thyroid storm, adrenal crisis) with chronic decisions in diabetes and bone disease.
DKA versus HHS
DKA: glucose usually >250 mg/dL, pH <7.30, bicarbonate <18, positive ketones, anion gap >10-12. HHS: glucose >600 mg/dL, osmolality >320, minimal ketosis, profound dehydration. For both: isotonic saline first, replace potassium once K <5.2 with urine output present, then start an insulin infusion. Add dextrose when glucose reaches 200-250 mg/dL in DKA.
Thyroid storm
Clinical diagnosis (Burch-Wartofsky score). Treat in sequence: beta-blocker (propranolol), thionamide (PTU preferred because it also blocks peripheral conversion), iodine at least one hour after the thionamide, hydrocortisone, and supportive care.
Adrenal crisis
Consider in fluid-refractory hypotension with hyponatraemia, hyperkalaemia, and hypoglycaemia. Draw cortisol and ACTH, then give dexamethasone 4 mg IV (does not interfere with the cortisol assay) or hydrocortisone 100 mg, plus 1 L of saline.
Diabetes
Metformin first line unless eGFR <30. SGLT2 inhibitors for heart failure or CKD; GLP-1 receptor agonists for atherosclerotic disease. Hold SGLT2 inhibitors during acute illness because of euglycaemic ketoacidosis. Individualise HbA1c targets, generally <7%.
Worked example
A 22-year-old with polyuria and vomiting: pH 7.10, HCO3 8, glucose 480 mg/dL, K 5.0, ketones positive. Begin 0.9% saline, add potassium to the fluids, start insulin at 0.1 U/kg/h, aim for a glucose fall of 50-75 mg/dL/h, and add 5% dextrose at 200-250 mg/dL. Bicarbonate is reserved for pH <6.9.
Traps that cost marks
- Giving iodine before a thionamide, which feeds hormone synthesis.
- Starting insulin before knowing the potassium in DKA.
- Missing euglycaemic DKA in a patient on an SGLT2 inhibitor.