COMPARATIVE STUDIES BETWEEN RENAL CLEARANCE OF NA-CR2CR(51)-ETHYLENEDIAMINE TETRAACETATE INULIN AND SODIUM THIOSULFATE IN HUMANS

Under standard clearance conditions we have compared the clearance of Cr51-EDTA with the clearance of Na-Thiosulfate in 47 patients with normal and impaired renal function and with the inulin clearance in 79 patients. Inulin was determined both by the Recorcinol and the Anthron method. A high degree of correlation was observed for both groups of comparative studies. Our results show that the clearance of Cr51-EDTA is slightly, but definitely lower than the clearance of Na-Thiosulfate or Inulin. The reasons for this difference are poorly understood. As the regression coefficients in the comparative study with Inulin and Na-Thiosulfate are not statistically different from each other, they may be averaged to obtain a correction factor. Radiation dosage to the patient is trivial and of no importance for the technical personal. We conclude that Cr51-EDTA may be used as a substitute for Na-Thiosulfate or Inulin. The clearance of Cr51-EDTA, however, has to be multiplied by 1.073 to obtain the true glomerular filtration rate. The accuracy and ease, with which Cr51-EDTA can be quantitated and the lack of chemical interference (glucose, mannitol, e.g.) are major advantages of Cr51-EDTA. © 1969 Springer-Verlag.