Measurement of glomerular filtration rate by means of a 99Tcm-DTPA complex and a scintillation camera: a method based on the kinetics of the distribution volume of the tracer in the kidney area.

Glomerular filtration rate (GFR) may be computed using the kinetics of the renal distribution volume curve Vt = Rt/Pt and a power fit of the plasma curve Pt = Pot-B. It can be demonstrated that GFR = d(Vt)/d(t)(1-B). The method is largely independent of background subtraction, allowing nonequivocal renal function determination in all cases. In a preliminary series of 20 patients, the linear regression coefficient of computed GFR with true clearance measurement by multiple blood samples method was 0.97 with a standard error on the estimate of the clearance of 5.5 ml.