OBSERVATIONS ON THE ANTIDIURETIC SUBSTANCE IN HUMAN SERUM

Abstract

LOYD and Lobotsky (1) reported that human serum contains an antidiuretic substance which can be detected by the method of assay developed by Birnie et al. (2), the serum being injected intraperitoneally into hydrated rats. They stated that “the activity of 1 cc. of human serum was usually of the order of that of 5 milliunits or less of Pitressin.” They gave no definite information about the antidiuretic titer found in individual cases, as they were concerned with the possible role of the ratio of this titer to the urinary concentration of corticosteroids in controlling water diuresis. However, examination of their figures shows that the majority of the sera tested did show considerable antidiuretic activity in rats. In particular, the greatest activity in normal adults was found following twelve hours’ dehydration. Considerable activity was also found in the sera of patients with adrenal deficiency. Slessor (3), using the same technique, also showed that the serum from normal subjects was antidiuretic after fourteen hours’ dehydration, and gave evidence of an even higher titer in the serum of patients with Addison's disease. Birnie et al. (2) were able to demonstrate an antidiuretic substance in the serum of normal and adrenalectomized rats. Dicker and Ginsburg (4) found that the antidiuretic substance in rat's serum was not present in plasma. Ames and van Dyke (5) concluded that the intraperitoneal technique employed by Birnie and associates (2) was an insensitive method and that the results were grossly at variance with those which they themselves obtained using an intravenous method of assay.