Some Factors Governing Renal Function.

Abstract

With the ultimate objective of finding a satisfactory method for the quantitative demonstration of impairment of renal function in humans, the authors have studied the rate of elimination of urea, as compared with the amount of urea in the blood and with the simultaneous excretion of water. The previous work of Ambard, 1 McLean, 2 and Addis, 3 and of the associates and critics of these experimenters, has been considered in detail.

In regard to the relationship of blood urea levels to rate of urea excretion, it will be recalled that there are two divergent schools of thought. The older group, of which Ambard and McLean are the outstanding examples, have shown that the rate of excretion is a parabolic function of the concentration of urea in the blood, according to the equation Ur = K√D. Ur = Gm. urea per liter blood. D = Gm. urea per 24 hr. (Measured over a short period and extrapolated for the 24 hours.) Addis, and later Adolph, 4 on the other hand, under conditions involving a large provocative ingestion of either urea of water, or both, have demonstrated a linear relationship, Ur = KD. Under ordinary conditions, however, the relationship approaches, but does not equal, the parabolic relationship proposed by Ambard.

By combining our own data with the normal cases reported by McLean and by Addis (excluding the cases where provocative doses had been given) we were able to calculate this relationship in 220 normal individuals. By simultaneous determination of the Pearson correlation coefficient, the correlation ratios and comparison of these with each other and with the probable error, according to the method of Blakeman, 5 it was possible to demonstrate that the relationship in these normal cases was not linear.