Exaggerated natriuresis in primary aldosteronism.

Acute response in blood pressure (BP) and natriuresis to saline infusion was evaluated in 16 patients with primary aldosteronism caused by aldosteronoma (PA) and 12 patients with salt-sensitive essential hypertension (SSEH). Salt-sensitivity was defined by a decrease in mean BP exceeding 5% at the second hour after a 20 mg furosemide injection. Plasma renin activity (PRA), plasma aldosterone concentration (PAC) and urine electrolytes in response to saline infusion were determined. During a 2-liter isotonic saline infusion, a similar degree of natriuresis and change in BP were observed in PA and SSEH patients. A significantly inverse correlation between the increase in mean BP and the degree of natriuresis at the end of the infusion was found in patients with SSEH (r = -0.80, p less than 0.01). No correlation was observed between these parameters in patients with PA (r = 0.28, p greater than 0.05). These results suggest that hypernatriuresis in SSEH may play a protective mechanism against abrupt increases in BP and volume during acute saline loading. This protective mechanism was not evident in patients with PA.