Individual Variations in the Relation between Urea Clearance and Creatinin Clearance

Abstract

SummaryEarlier investigators (HAYMAN, HALSTED and SEYLER, BJERING, COPE) have shown that the relation between urea clearance and creatinin clearance is fairly constant in both healthy persons and renal patients and that it lies at about 0.50.Examples are given, whereafter it is shown that in some patients with »nephrosis» there are considerable individual variations from the normal value, so that sometimes the relation is found to be constant at about 0.25 and at other times about 0.75, the examinations being spread over periods up to more than three years. In all cases the individual patient also shows a distinctly wide margin between the figures, for which no explanation can be offered as a rule, for it can be seen to be due neither to variation in diuresis nor to dietetic changes. According to the present view of the excretion of the two substances, the variations must presumably be the result of the changes in the tubules, and whereas the creatinin clearance provides an indication of changes in the glomerular function, the urea clearance thus provides a measure of the sum of the changes in glomeruli and tubuli.The authors discuss the applicability of »standard clearance», and suggest that it should at any rate only be employed when the concentration index for urea is above 75.