Validity of the endogenous creatinine clearance as a measure of glomerular filtration rate in the diseased human kidney.

Twenty-five years ago Rehberg proposed the exogenous creatinine clearance for the measurement of glomerular filtration rate (1). In the dog and rabbit, this clearance provides a simple and accurate method of determining the filtration rate, coinciding with the inulin and ferrocyanide clearances (2, 3). Subsequently, Shannon (4) and Miller and Winkler (5) found in man that the exogenous creatinine clearance was considerably higher than the glomerular filtration rate.6 Despite the fact that the compound he chose did not provide an exact measure of the glomerular clearance in man, Rehberg's pioneering development opened a whole new area of research in renal dynamics. Unfortunately, the unreliability of exogenous creatinine and ferrocyanide (7) clearances in man left only inulin for the measurement of filtration rate in the human kidney. The determination of inulin clearance has several serious disadvantages. It was inevitable, therefore, that the search for simpler methods of measuring glomerular filtration rate in man would continue. It occurred to one of us some years ago that the endogenous creatinine clearance might prove to be a true measure of the filtration rate.