Endocrine Disorders
Diabetes and DKA
Type 1 diabetes is managed with basal-bolus insulin; target HbA1c is generally below 7%. Diabetic ketoacidosis: restore volume with isotonic fluid, begin an insulin infusion at 0.05–0.1 units/kg/hour after the initial fluid bolus, and add dextrose when glucose falls toward 250–300 mg/dL so the insulin can continue clearing ketones. Potassium must be replaced once urine output is confirmed, since insulin drives potassium intracellularly. Cerebral edema is the feared complication - watch for headache, bradycardia, and declining mental status; treat with mannitol or hypertonic saline and avoid rapid osmolar shifts.
Thyroid disease
Congenital hypothyroidism requires immediate levothyroxine at 10–15 mcg/kg/day; delays cause irreversible cognitive impairment. Recheck TSH and free T4 at 2–4 weeks. Separate levothyroxine from calcium, iron, and soy by at least 4 hours. For Graves disease, methimazole is preferred in children; propylthiouracil is reserved for the first trimester and thyroid storm because of hepatotoxicity.
Adrenal and growth disorders
Adrenal insufficiency: hydrocortisone 10–15 mg/m2/day divided three times daily, with stress dosing (roughly 50–100 mg/m2/day) during illness or surgery. Congenital adrenal hyperplasia adds fludrocortisone and sodium chloride in infancy. Central precocious puberty is treated with a GnRH agonist such as leuprolide.
Worked example
A 10 kg newly diagnosed infant with congenital hypothyroidism: levothyroxine 10–15 mcg/kg/day = 100–150 mcg daily. Dispense a formulation that allows accurate measurement (tablet crushed in a small volume of water or liquid), give on an empty stomach, and avoid coadministration with formula, iron, or calcium.