THE SPECIFICITY OF THE “WATER TEST“ AS A DIAGNOSTIC PROCEDURE IN ADDISON'S DISEASE1

Abstract

IN 1941 two procedures to assist in the recognition and exclusion of Addison's disease were described by Robinson and two of us [Power and Kepler (30)]. These procedures have since become known as the “water test.” It is the purpose of this review to consider the rationale of the test and to evaluate it specificity in the diagnosis of chronic adrenal cortical insufficiency. Data obtained at the Mayo Clinic during the period from January, 1941, to May, 1945, inclusive, have been utilized. The two procedures which comprise the “water test” were considered separately and in combination. I. DESCRIPTION OF TESTS AND INTERPRETATION The following description and interpretation of the water test are reproduced in part from the original article of Robinson, Power and Kepler (30). Procedure I (based on volume of urine).—On the day before the test the patient eats three ordinary meals but omits extra salt. He is requested not to eat or drink anything after 6 p.m. Until this time he may drink water as desired. At 10:30 p.m. lie is requested to empty his bladder and discard the urine. All urine which is voided from then on until and including 7:30 a.m. is collected. The volume of this urine is measured and it is saved for chemical analysis. Breakfast is omitted. The patient is asked to void again at 8:30 a.m. and immediately thereafter he is given 20 cc. of water per kilogram of body weight (9 cc. per pound). He is asked to drink this within the next forty-five minutes. At 9:30, 10:30 and 11:30 a.m. and 12:30 p.m. he is requested to empty his bladder. In order to eliminate the effects of exercise and posture on urinary excretion, he is kept at rest in bed except when up to void. Each specimen is kept in a separate container. The volume of the largest one of these four specimens is measured. Under these conditions some patients having Addison's disease exorete so little urine that they- are unable to void more than once or twice during the entire morning. …