Comparison between Two-sample Method with ^99mTc-diethylenetriaminepentaacetic acid, Gates' Method and Estimated...

Glomerular filtration rate (GFR) is the most important parameter for the assessment of renal function. GFR by plasma sampling technique is considered accurate in the selection of donors for renal transplantation. Estimated GFR (eGFR) calculations using Gates' method and Modification of Diet in Renal Disease (MDRD) and Cockcroft-Gault (CG) equations are simple methods but have not been validated in the Indian population. Hence, we aimed to assess the correlation between these three techniques.

The plasma sampling technique was done using two samples at 60 and 180 min after injection of 1 mCi (37MBq) ^99mTc-diethylenetriaminepentaacetic acid (^99mTc-DTPA) in 66 healthy donors. Age, sex, height, weight, and plasma creatinine were recorded. Normalized GFR (nGFR) by two-sample method and eGFR (for Gates', MDRD, and CG) values were calculated using formulae.

There were 14 male and 52 female donors. Mean age was 46.56 ± 12.88 years (24-69 years). Mean height was 153.74 ± 8.35 cm, whereas mean weight was 56.97 ± 11.88 kg. Mean nGFR value was 80.4 for two-sample method while mean eGFR value for Gates', CG, and MDRD were 83.3, 89.36, and 97.47 ml/min/1.73 m² (eligibility value at our institution = 70), respectively. While the correlation between nGFR and eGFR CG and MDRD was weak moderate (correlation coefficient = 0.5), nGFR and eGFR Gates' had a moderate correlation (0.686). Mean total bias for eGFR Gates', CG, and MDRD were 2.87, 8.93, and 17.0, respectively. P₃₀ of eGFR Gates', CG and MDRD were 60.6%, 57.6%, and 62.1%, respectively.

Due to the large variability in eGFR Gates', CG and MDRD, nGFR estimation using the plasma sampling technique with ^99mTc-DTPA appears necessary while screening healthy donors for renal transplantation.