Calculation of Glomerular Filtration Rate from Renal Volume in Kidney Donors using Hert's Formula

Abstract

Introduction: The incidence of Chronic Kidney Disease (CKD) is rising throughout the world, and with it, the need for kidney transplants. The 'Gold Standard' in measuring Glomerular Filtration Rate (GFR) in potential kidney donors remains a renogram. In many countries, access to this technology remains limited and expensive. We evaluated a Computed Tomography (CT)- based method of calculating the GFR using estimated renal volume, as first described by Herts' et al. Aim: To compare differential renal function as assessed by isotope renal scan using 99mTc Diethylene-Triamine-Penta-Acetic Acid (DTPA) with CT scan measured differential renal volume. Further, we aimed to compare and correlate the CT scan measured volume based GFR, with GFR estimated using Modification of Diet in Renal Diseases (MDRD) and Cockcroft-Gault (CG) methods. Materials and Methods: A total of 61 healthy donors (47 female, 14 male) were studied. Standard contrast CT scan was performed using non-ionic iodinated contrast. Special volumetric 3D analysis was used to calculate the volume. Herts formula was used to calculate the GFR. DTPA renogram was done on all patients with a Gamma Camera. The results were compared with MDRD and CG estimated GFR on all patients using Analysis of Variance (ANOVA) and Tukey Post-Hoc Test. Results: The Volume Calculated-GFR correlates better with total GFR than GFR calculated by CG and MDRD formulae. Conclusion: The Herts formula based GFR correlated well with estimated GFR values and may be used in circumstances were access to DTPA renograms is expensive or unavailable.

Keywords

• chronic kidney disease
• cockcroft-gault formula
• kidney transplant