Previous studies have reported an exaggerated natriuresis in hypertensive man; however, a systematic appraisal of this response in various forms of hypertension has not been made. We measured fractional excretion of sodium (FENa) during a four hour intravenous infusion of 2 liters normal saline in 162 normal subjects and 120 hypertensives. Of these, 13 had primary aldosteronism (ALDO), 19 high ...