Endocrine
What you must know
Diabetes: diagnose with A1c 6.5% or higher, fasting glucose 126 or higher, 2-hour glucose 200 or higher, or random glucose 200 or higher with symptoms; confirm an asymptomatic abnormal result. Metformin is first-line; add a GLP-1 receptor agonist or SGLT2 inhibitor when atherosclerotic disease, heart failure, or chronic kidney disease is present. Individualize A1c targets and deintensify in frail older adults with hypoglycemia risk. Distinguish DKA (glucose often over 250, ketones, pH under 7.3, elevated anion gap) from hyperosmolar hyperglycemic state (glucose often over 600, high osmolality, minimal ketosis).
Thyroid: order TSH first. Low TSH with high free T4 means hyperthyroidism; Graves disease adds diffuse goiter, ophthalmopathy, and a stimulating antibody. Thyroid storm is a clinical diagnosis treated with beta-blockade, thionamide, iodine after the thionamide, and steroids. Myxedema coma requires hydrocortisone before levothyroxine to avoid precipitating adrenal crisis. Adrenal insufficiency: cosyntropin stimulation confirms; treat with glucocorticoid before thyroid hormone in any hypotensive patient.
Calcium and bone: primary hyperparathyroidism shows high calcium, low phosphate, and inappropriately high PTH; hypercalcemia of malignancy shows suppressed PTH. Osteoporosis treatment thresholds follow DXA and fracture risk. Pituitary disease presents with field deficits or hypopituitarism.
Traps
- Missing euglycemic DKA in a patient on an SGLT2 inhibitor.
- Given levothyroxine before hydrocortisone in myxedema coma.
- Trusting A1c in anemia, hemoglobinopathy, or recent transfusion.
- Assuming a normal TSH excludes central hypothyroidism.
Rule of thumb
In an endocrine emergency with hypotension, give hydrocortisone before levothyroxine - every time.