Aldosterone and blood pressure in obese subjects during short-term starvation.

Changes in plasma renin activity (PRA) and aldosterone concentration during 10 days of starvation were studied, together with the relationship among PRA, aldosterone, plasma volume, sodium balance and mean blood pressure (MBP). Study subjects were 16 obese individuals (13 females and 3 males; age ranged 18-50 years) with a body mass index greater than 30 kg/m2. Total fasting induced a significant decrease in body weight, MBP, plasma volume and urinary sodium concentration, and a rise in PRA and aldosterone concentration. Before starvation, there was a significant correlation between aldosterone concentration and MBP. This data support the hypothesis that aldosterone is one of the factors which elevate blood pressure in obese subjects. Much of the initial fall in blood pressure during starvation seemed to be due to an imbalance between the cessation of sodium intake and excessive natriuresis.