Response of normal subjects to prolonged high fluid intake

Abstract

In order to test the hypothesis that the great variability seen in the serum osmolality characteristic of different normal persons is a result of fluid intake habits, four healthy male subjects ingested increasing amounts of fluid over a 4-week period reaching an average daily intake of approximately 8.5 liters during the 4th week. Serum osmolality measured repeatedly in the early morning and during weekly 6.5-hr water-deprivation tests did not vary significantly from that of control periods. It is concluded that in normal individuals fluid intake does not influence the “setting” of serum solute concentration. serum osmolality homeostasis; serum solute concentration in water loading; water intoxication; renal concentrating capacity; fluid balance; water regulatory mechanisms Submitted on June 25, 1963