A comparison of methods in measurement of effective renal plasma flow and glomerular filtration rate in clinical practice.

Abstract

Using a single injection clearance method as a reference test, 24-hour creatinine clearance and gamma camera estimation of ERPF and GFR were compared in a sample of the Japanese adult patient population. The reference tests included ERPF with I-131 OIH and GFR with In-111 DTPA, single blood sample, and 1-hour external counting over the heart for each tracer. The 24-hour creatinine clearance and gamma camera methods were equally accurate in estimating GFR or ERPF compared with the clearance methods. The gamma camera methods were less accurate for GFR than ERPF. Among many gamma camera estimation formulas for GFR, the renal Tc-99m DTPA uptake best correlated with the reference GFR (compared to Schlegel's GFR or Gates' GFR). The authors found that the simpler the procedure and data processing, the better the results. Origin of errors in estimating ERPF and GFR, the procedures of choice, patient population studied, quality control achievable in clinical practice, and the clinical situations the clinicians are likely to encounter are discussed.