Plasma renin activity and mineralocorticoid replacement therapy in congenital adrenal hyperplasia.

Plasma renin activity and serum concentrations of sodium and potassium were repeatedly measured in seven children with congenital adrenal hyperplasia due to steroid-21-hydroxylase deficiency, to monitor the sodium balance during treatment. Infants with the salt-losing form had high plasma renin activity levels 5--11 months after subcutaneous implantation of a pellet containing 100 mg deoxycorticosterone acetate. These elevated plasma renin activity levels were suppressed to the normal range by repeated implantation of DOCA pellet. Moderately elevated values of plasma renin activity in older salt-losers normalized after increasing the dietary sodium intake. Plasma renin activity level has superiority over serum electrolyte concentrations as an index of mineralocorticoid deficiency.