Isolated glucocorticoid deficiency: metabolic and endocrine studies in a 5-year-old boy.

A 5-year-old boy is described who presented with episodes of hypoglycaemia triggered by mild infections or fever. Subnormal glucocorticoid production was confirmed by demonstrating low urinary excretion of free cortisol, low plasma cortisol concentrations that did not rise after glucagon and ACTH stimulation, and by elevated plasma ACTH levels. The selective nature of the abnormality was confirmed by demonstrating normal plasma electrolyte concentrations and blood pressure on a salt-restricted diet. Plasma renin activity and plasma aldosterone levels were also normal and responded appropriately to salt restriction and to frusemide-induced diuresis. Starvation-induced hypoglycaemia was associated with raised levels of blood ketone bodies and low blood alanine concentrations. Catecholamine secretion during hypoglycaemia was reduced. Glucocorticoid replacement therapy was effective in restoring normal glucose homeostasis.