Estimating Glomerular Filtration Rate in Overweight and Obese Malaysian Subjects

Background and Aims: 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.

Methods: 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.

Results: 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 subjects' weight (p=0.036), it didn't with their BMI (p=0.302).

Conclusions: The MDRD-based formulae were better in estimating GFR in overweight and obese Malaysian subjects. GFR correlated with subjects' weight rather than BMI.