Comparison of double plasma sampling method and gates method for estimation of glomerular filtration rateComparison of double plasma sampling method and gates method for estimation of glomerular filtration rateComparison of double plasma sampling method a

Abstract

Glomerular filtration rate (GFR) is an important indicator of renal function. Several methods have been applied to calculate GFR in clinical exams. In this study, we evaluated and compared between radionuclide plasma sampling methods (double blood samples, in vitro methods) and in vivo Gate’s method using 99mTc-diethylene triamine penta-acetic acid (99mTc-DTPA) renography. Subejct and method: 42 patients were participated in this study, including 12 patients with obstructive uropathy (group 1) and 30 renal donors (group 2). The administered doses were in a range of 5 – 7mCi. Then, scintigraphy was performed simultaneously after injection, and GFR was calculated by Gate’s method. Blood samples were collected at 60 mins and 120 mins post-injection, which were counted by a thyroid uptake system, and GFR results were determined using a double plasma sample (DPSM) method. Result: The mean GFRs calculated by renography in groups 1 and 2 were 85.8 ± 16.2 (ml/min) and 118.9 ± 13.9 (ml/min), respectively. Meanwhile, using the in vitro DPSM, the mean GFRs in group 1 and 2 were 73.8 ± 15.4 (ml/min) and 117.0 ± 13.0 (ml/min) respectively. They showed a high correlation between the two methods in the two groups (r = 0.86 and 0.71, respectively). Conclusion: Renography is a simple technique but considered inaccurate for determination of GFR. However, in vitro DPSM is rarely used in Vietnam. In this study, Gate’s method corresponded well with plasma sampling method and tended to overestimate the glomerular filtration rate.