Determining an accurate method to estimate GFR in renal transplant recipients with stable serum creatinine levels

Detecting renal allograft dysfunction early will allow timely diagnosis and treatment. There is no objective recommendation by national kidney societies for glomerular filtration rate (eGFR) estimation in post-transplant setting. 99mTc-DTPA Technetium-99m Diethylene triamine penta acetic acid) renogram can identify early renal dysfunction much before serum creatinine levels get deranged. Our objectives are: 1) We hypothesised that if Gates formula is depth corrected for anteriorly placed renal allograft, can it serve as a reliable, accurate investigation 2) To compare how DTPA renogram with depth correction (CT based) and without depth correction (fixed distance) fares with creatinine based MDRD (Modification of Diet in Renal Disease), and CKD-EPI Chronic Kidney Disease Epidemiology Collaboration) equations in transplant recipients in our population. GFR values were compared with gold standard venous blood GFR single sampling method in a few patients.  Forty adults live related adult renal allograft recipients with serum creatinine values of less than 2.0 mg/dl at 6 months follow-up were enrolled. Mean measured GFR was calculated for 4 different methods along with single plasma sampling method. MDRD and CKD-EPI equations showed higher values in our study but correlated well with each other in GFR estimation. Accuracy was highest with GFR derived from depth corrected DTPA renogram (69.2%) than for fixed depth method (60 %, p ¼ 0.0012). GFR obtained by DTPA depth correction method also showed good correlation to SPSM. 99mTc-DTPA based GFR estimation with depth correction is not affected by serum creatinine level and showed highest accuracy.