ON THE RENAL EXCRETION OF XYLOSE 1

Abstract

The excretion of xylose was studied by a method previously used, which determines the time change of plasma concn. and rate of output of the substance during their phase of exponential decrease, establishes the linearity of the relation between these two quantities, supplies the necessary constants, and gives explicit information on the errors of observation. The excretion constant of xylose, calculated from data on 2 human subjects, is 0.77, when the plasma concn. (x) is measured in mgm. per 100 cc. and the rate of output (y) in mgm. per min. This constant is independent of moderate exercise and moderate changes in diuresis. It is shown that the ratio of the 2 quantities (y/x) is disturbed not only by accidental errors of observation (and the larger errors are in the denominator), but also systematically by the fact that the straight line satisfying the relation between y and x does not go through the origin of the coordinate system.