THE SIGNIFICANCE OF THE SECRETION OF ALDOSTERONE DURING DIETARY SODIUM DEPRIVATION IN NORMAL SUBJECTS*

Abstract

The excretion of aldosterone in urine was studied in 11 instances of dietary sodium deprivation in 6 young males. In several instances, there was a lag before the excretion of aldosterone increased. The maximal, as well as the mean, levels of aldosterone excretion attained were highly variable from individual to individual and bore little relationship to the efficiency with which the adaptation to the low-sodium diet took place. In 9 out of 11 cases, the urinary aldosterone fell after a maximum had been reached, although not necessarily to control levels, despite continuing improvement of sodium retention by the kidney. The suddenness of the sodium deprivation seemed to play a role in the extent of the ensuing rise in aldosterone. Resumption of a normal-sodium diet was initially accompanied by efficient sodium retention, although aldosterone excretion in the urine had already decreased to values near or within control levels. These observations suggest the importance of factors other than the amount of aldosterone secreted, in the regulation of sodium excretion by the normal kidney.