Background: Estimated glomerular filtration rate (eGFR) equations are essential for the kidney function’s classification.Currently these equations have been validated in some races such as Causasian, African-Americans, Chinese, including Thais.The reexpressed Modification of Diet in Renal Disease equation for Thais is as follow: 175 x Cr enz[superscript (-1.154)] x Age[superscript (-0.203)] x 0.742 (if female) x 1.129 (if Thai) and we used multiple regression analysis, The Thai eGFR formula is: 375.5 x Cr enz[superscript (-0.848)] x Age[superscript (-0.364)] x 0.712 (if female). In Thai study, the mean body mass index is 25.3±4.8 kg/m2. These equations can be applied to the obese populations whether or not. Therefore, we examined all eGFR equations available: Reexpressed MDRD equation, Thai eGFR formula, etc. Methods: A total 104 adults Thai obese patients and candidates (BMI >=30 kg/m²) were enrolled. The 99mTc-DTPA plasma clearance was used as a reference for GFR.The serum creatinine that was determined by IDSM reference enzymatic method (Cr enz) was applied to equation to these eGFR equations to compare accuracy and precision. Results: The disagreement between the reference GFR and eGFR (reference GFR minus eGFR) was 15.6 ml/min/1.73 m² for the reexpressed MDRD equation, 13.1 ml/min/1.73 m² for CKD–EPI equation, 2.6 ml/min/1.73 m² for the eGFR from the reexpressed MDRD with Thai racial facto and 12.1 ml/min/1.73 m² for Thai eGFR formula. The thai coefficient for reexpressed MDRD was 1.117. Conclusions: Differrences in race, age, creatinine can significantly affect the results obtained from eGFR equation, However the body mass index (BMI) may affect the results but not statistically significant. The validation of reexpressed MDRD with Thai racial factor correction and Thai eGFR equation can precisely apply to predict eGFR in Thai obese populations.
