Low-renin hypertension in young infants.

Plasma renin activity (PRA) in neonates is significantly higher than in older infants and children and may increase as a result of numerous physiologic or therapeutic factors. For these reasons, the measurement of PRA is not usually helpful in establishing the cause of hypertension in neonates. In conditions that suppress renin release, however, measurement of PRA can be most useful. Herein, we describe two infants (ages 4 and 5 months, respectively) with sustained hypertension and low PRA secondary to dexamethasone-suppressible hyperaldosteronism. Low PRA was essential in establishing this diagnosis in both patients. Dexamethasone-suppressible hyperaldosteronism should be considered in hypertensive infants who have normal genitalia and low PRA.