Renal Concentration Test Employing Use of Pituitary Extracts. Response of Normal Subjects

Abstract

The various concentration tests for renal function in use today consist primarily of some form of water restriction sufficient to reduce urinary volume. The specific gravity of urine is thereby elevated a variable degree depending upon tubular function and the degree of water restriction. We have attempted to shorten or abolish the long period of water deprivation necessary in concentration tests by the use of the antidiuretic action of posterior pituitary extracts. The effectiveness of posterior pituitary extracts in raising the specific gravity of the urine has recently been shown in dogs by Paine and Nelson. 1 Comparison of a standard concentration test for renal function with the use of posterior pituitary extracts was obtained by submitting patients to three or more of the following 5 procedures: (1) A modified Fishberg concentration test with restriction of fluids from 6 o'clock the previous evening. The overnight urine was discarded and half-hourly specimens collected from 9 o'clock in the morning until 11 or 12 noon; (2) the same procedure with the administration of 0.5 cc (10 units) of surgical Pituitrin subcutaneously at 9 o'clock in the morning; (3) free access to fluids until 9 in the morning when they were restricted; the Pituitrin administered and 30-minute specimens taken as above; (4) free access to fluids until 9 in the morning when, in 15 minutes, 1,600 cc of water were given followed by administration of 0.5 cc of surgical Pituitrin; specimens of urine were again collected at half-hourly intervals; (5) the fourth procedure was repeated without the administration of the Pituitrin. Specific gravities were obtained by weighing the urine in a 2 cc weighing bottle or pyknometer to 0.1 mg and comparison made with a similar quantity of distilled water at the same temperature according to the usual technic. 2

Fifty-two experiments have been carried out on 15 normal individuals. Consistent results have been obtained in all. Fig. 1 shows the results in one subject. The curves are numbered to correspond to the procedures described above. In this instance, the test was carried out in very hot weather, which accounts for the fact that with or without preparation the urinary specific gravity started in each experiment in a range (above 1.025) indicative of satisfactory renal function.