THE EXCRETION OF CREATINE AND CREATININE BY WOMEN

Ever since the introduction of a rapid accurate colorimetric method by Folin in 1904 for the estimation of creatinine in the urine, this nitrogenous excretory product has been the subject of extensive investigation and physiologic speculation. It is well established that creatinine is an end-product of endogenous protein metabolism, though the precise precursors and the processes whereby it arises in the body when there is no intake of creatine or creatinine remain to be definitely demonstrated. Several features of decided interest have become familiar. The foremost of these is the constancy of the endogenous creatinine output. Despite wide variations in the nitrogenous intake ranging between such extremes as 5 and 20 Gm. a day in a creatine-free and creatinine-free diet, the quantity of creatinine eliminated in the urine ordinarily shows insignificant variations from day to day in the same person though it varies with different individuals. The number of milligrams