Hypoglycemia in a Two-Year-Old Boy with Adrenocorticotropic Hormone (ACTH) Deficiency (Probably Isolated) and Adrenal Medullary Unresponsiveness to Insulin-Induced Hypoglycemia

A 2-yr-old boy in whom hypoglycemia was associated with an ACTH deficiency (probably isolated) and with adrenal medullary unresponsiveness to insulin-induced hypoglycemia is described. This patient may represent the first reported clinical analogue to experimental studies demonstrating that the activity of phenylethanolamine-N-methyl transferase is controlled by glucocorticoids. Phenylethanolamine-N-methyl transferase is highly localized in the mammalian adrenal medulla and catalyzes the N-methylation of norepinephrine to epinephrine. Treatment of our patient's adrenal cortical insufficiency with glucocorticoids corrected his adrenal medullary response to insulin-induced hypoglycemia. The etiology of the patient's possibly isolated ACTH deficiency is unknown.