Estimating Glomerular Filtration Rate in Overweight and Obese Malaysian Subjects

Overweight and obesity are significant risk factors for chronic kidney disease (CKD). Glomerular filtration rate (GFR) is the best index of renal function. We evaluated the accuracy of the Cockroft-Gault, MDRD and modified MDRD formulae in predicting GFR in overweight and obese subjects and also determined the relationship between Body Mass Index (BMI), weight and GFR. Healthy volunteers with BMI ≥23kg/m² were recruited and subjected to blood and urine investigations, renal ultrasonography and 99mTc-DTPA renal scan. The correlation, accuracy and precision of the eGFR derived from each formula were compared with reference GFR as determined by 99mTc-DTPA. A total of 101 subjects with a median weight of 74.0kg (68.0-84.7) and median BMI of 29.6 kg/m² (27.2-33.2) were recruited. Their mean GFR 99mTc-DTPA was 120.3± 24.5ml/mm/1.73m². Although the eGFRs derived from all formulae correlated with GFR 99mTc-DTPA, only those derived from the MDRD and modified MDRD had small biases and better precision in estimating GFR. While GFR significantly correlated with the subject's weight (p=0.036), it didnt with their BMI (p=0.302). The MDRD-based formulae were better in estimating GFR in overweight and obese Malaysian subjects. GFR correlated with subject's weight rather than BMI.