Correlation between the Biological Value of Protein and the Percentage of Creatinine N in the Urine

Abstract
It is believed that the high degree of correlation between biological values and creatinine nitrogen percentages in the urines of the last days of any given period of protein ingestion entitles this constituent of urinary nitrogen to consideration as a baseline of reference for the evaluation of proteins. With a very poor protein the amount of nitrogen appearing in the urine is large; the creatinine portion of the total nitrogen therefore is a small percentage; and vice versa for a good protein. The correlations arrived at in these experiments lend themselves to prediction of biological values from creatinine nitrogen percentages. A higher coefficient of correlation in the short series of experiments with only three dogs, as contrasted with the longer series involving from 6 to 12 dogs, is to be ascribed to the refinements of the method for creatinine determinations evolved by Clark and Thompson. The result is a safer prediction and therefore a closer estimate of B.V.
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