Urea clearance tests.

This paper has its origin in work done in a prisoner of war hospital camp in Siam. Under the prevailing condition of protein-starvation there the Van Slyke formulae for calculating urea clearance as a percentage of normal were found to be completely misleading. The only literature then available was a handbook of laboratory methods giving the bare routine of the test without indicating the source of factors in the formulae. Therefore an attempt was made to devise our own standards, including adjustment for the rate of tirine excretion. When eventually I was able to obtain copies of the principal papers by Van Slyke and his colleagues (Austin et al., 1921 ; McIntosh et al., 1928; Moller et al., 1928) it seemed of interest to compare our results with theirs. The initial objective was to see if the method of adjustment for the rate of urine excretion used in Siam, or a modification of it, might provide a single generally applicable formula by which procedure could be both simplified and unified in place of the two in current use. This objective was achieved (see appendix), but in the course of the work I found myself forced to the conclusion that the Van Slyke urea clearance test is useless in its present form.