THE EFFECT OF URINE VOLUME ON UREA EXCRETION

Abstract

The "maximum" and "standard" urea clearance formulae of Moller, Mclntosh, and Van Slyke were compared with formulae proposed by Bing, by Williams, and by Dole for estimating the effect of urine vol. on urea clearance. The accuracy of the respective formulae was estimated by comparing the constancy with which the maximal clearance, obtainable with high urine vol., could be calculated from clearances observed with lower urine vols. by the respective formulae for each of a number of normal and nephritic subjects. The formulae of Bing and of Williams proved to be less accurate than those of Moiler et al. and of Dole. The conceptions of Dole''s theoretically derived formula have been used to explain, from increased permeability of damaged renal tubules, the different effects of urine vol. on urea excretion in different nephritic subjects, and the loss in nephritis of ability to excrete urine of high urea conc. Examples are given indicating that, by observing the effect of urine vol. on urea clearance in nephritic patients, it may be possible to estimate the urine vol. flow required for optimal urea excretion.