The effect of normalization of sodium balance was evaluated in children with aldosterone deficiency of several etiologies. In salt-losing congenital adrenal hyperplasia (CAH), treatment with a mineralocorticoid in doses that normalized plasma renin activity (PRA) induced a marked increase in linear growth. Serum 17-hydroxyprogesterone (17-OHP) and androgens fell further when adequate sodium balance was achieved, allowing in some cases a reduction in glucocorticoid replacement dose. Together with PRA measurement they were the most sensitive indicators of adequate mineralocorticoid and glucocorticoid replacement therapy. In 2 teenage children with aldosterone deficiency due to Addison's and autoimmune polyglandular disease similar improvement in growth as well as onset of puberty occurred when sodium balance was normalized by increased mineralocorticoid therapy. These studies show that adequate sodium balance is essential for normal growth and pubertal development.