DETERMINATION OF URINARY EXCRETIONS OF ALDOSTERONE AND SODIUM BY SHORT-TERM COLLECTIONS OF URINE IN HEALTHY-MEN

The study was designed to evaluate the usefulness of urinary aldosterone and sodium excretions (AER and UnaV) determined for 4- and 12-hour period in providing an accurate reflection of daily AER and UNaV. Nine healthy young male volunteers were fed diets which contained varying amount of sodium for a period of 4 days; 34 mEq/day as low-salt, 450 mEq/day as high-salt and 194 mEq/day as control diet. Urine collection was made every 4 hours starting at 8:00 a.m. for 24 hours on the last day of each period. The values for 12-and 24-hour urine were obtained by the sum of those for 4-hour collections. The values for both AER and UnaV for every 4-hour showed remarkable circadian rhythms in any of 3 different dietary sodium intakes. The correlation between any 4-hour value for AER or UNaV and 24-hour value was highly significant [formula omitted]. The values for AER or UNaV, expressed per gram creatinine excretion, also revealed highly significant correlation between any 4-or 12-hour and 24-hour period [formula omitted]. Highly significant correlations were also observed between the “supine” plasma aldosterone concentration and the preceding 12-hour [formula omitted] or 24-hour AER [formula omitted]. It can be concluded that AER and UnaV measured in 4-hour or 12-hour period are a valid reflection of AER and UnaV for 24 hours. © 1979, The Japanese Circulation Society. All rights reserved.