METHOD OF ASSAY OF A SODIUM-RETAINING FACTOR IN HUMAN URINE1

Abstract

THE retention of salt and water in a number of clinical conditions has sometimes been attributed to the presence of an excess of a desoxycorticosterone- like substance possibly of adrenal cortical origin. It has also been suggested that other conditions, among them certain rheumatic diseases, may be associated with a relative excess of “mineralocorticoid” (Selye 1951). For some time the validity of these suggestions could not be investigated because a sensitive method for the assay of this material was not available. Dorfman, Potts and Feil (1947) found that the urinary excretion of Na²⁴, during the first 6 hours after its subcutaneous injection in adrenalectomized rats, could be reduced by pretreatment with as little as 1 jug. microgram of desoxycorticosterone-acetate (DCA). A dose-response curve was not given and the effects were not always reproducible. However, the principles suggested by these investigators have been used as a basis for a biological assay procedure by several groups of investigators. None of the modifications