Pediatric Endocrinology and Metabolism
Endocrinology items test protocol recall: how to run a diabetic ketoacidosis resuscitation safely, when to start levothyroxine in congenital hypothyroidism, how congenital adrenal hyperplasia presents, and which auxological pattern points to an endocrine cause of short stature.
Diabetic ketoacidosis
- Criteria: glucose above 200 mg/dL, pH below 7.3, bicarbonate below 15 mmol/L, with ketonaemia.
- Give 10 mL/kg isotonic saline first. Start an insulin infusion at 0.05-0.1 units/kg/hour after one hour; do not give an insulin bolus. Add dextrose when glucose falls to 250-300 mg/dL and replace potassium once urine output is established.
- Cerebral oedema: headache, bradycardia and hypertension during treatment. Slow the fluids, give mannitol 0.5-1 g/kg, and avoid rapid osmotic shifts.
Thyroid disease
Congenital hypothyroidism is detected on newborn screening. Start levothyroxine 10-15 micrograms/kg/day within two weeks of life; delay causes irreversible intellectual disability.
Adrenal disease
Congenital adrenal hyperplasia from 21-hydroxylase deficiency presents with salt wasting, hyperkalaemia, hyponatraemia and ambiguous genitalia in a 46,XX newborn. Confirm with 17-hydroxyprogesterone. Treat with hydrocortisone, fludrocortisone and sodium chloride, and give stress doses during illness.
Growth and puberty
- Turner syndrome: short stature, webbed neck, coarctation; confirm by karyotype.
- Precocious puberty: breast budding before 8 years in girls or testicular enlargement before 9 years in boys; treat with a gonadotropin-releasing hormone analogue.
- Delayed puberty: no breast development by 13 years in girls or no testicular enlargement by 14 years in boys.
Metabolic disease
Phenylketonuria is detected on screening and managed with a phenylalanine-restricted diet. Galactosaemia requires exclusion of galactose. Consider an inborn error when a neonate deteriorates after feeding with vomiting, lethargy and acidosis.
Worked example
A 9-year-old with new diabetes presents drowsy with glucose 480 mg/dL, pH 7.12, bicarbonate 8 mmol/L and ketonuria. Give 10 mL/kg saline, then an insulin infusion at 0.05 units/kg/hour; do not bolus. Add potassium and, once glucose reaches 250-300 mg/dL, add dextrose while continuing insulin until the acidosis clears. Monitor neurologically; sudden headache with bradycardia means cerebral oedema and needs mannitol and fluid rate reduction.
Traps
Giving a bolus insulin dose in paediatric ketoacidosis, stopping insulin when glucose normalises before the acidosis resolves, and delaying levothyroxine in a screened positive newborn.