BACKGROUND - Urinary excretion of bisphenol A (BPA) and alkylphenols (APs) was used as a biomarker in most previous studies, but no study has investigated whether urinary excretion of these environmental phenols differed by renal function.
OBJECTIVE - We estimated the association between renal function and urinary excretion of BPA and APs.
METHODS - Analyses were conducted using data from the National Health and Nutrition Examination Survey (NHANES) 2003-2006. Renal function was measured as estimated glomerular filtration rate (eGFR) calculated by the Modification of Diet in Renal Disease (MDRD) Study equation and by the newly developed Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Regression models were used to calculate geometric means of urinary BPA and APs excretion by eGFR category (≥ 90, 60-90, < 60 mL/min/m(2)) after adjusting for potential confounding factors.
RESULTS - When we used the MDRD Study equation, participants without known renal disease (n=2,573), 58.2% (n=1,499) had mildly decreased renal function or undiagnosed chronic kidney disease. The adjusted geometric means for urinary BPA excretion decreased with decreasing levels of eGFR (p for trend=0.04). The associations appeared primarily in females (p for trend=0.03). Urinary triclosan excretion decreased with decreasing levels of eGFR (p for trend < 0.01) for both males and females, and the association primarily appeared in participants < 65 years of age. The association between BPA and eGFR was nonsignificant when we used the CKD-EPI equation.
CONCLUSIONS - Urinary excretion of triclosan, and possibly BPA, decreased with decreasing renal function. The associations might differ by age or sex. Further studies are necessary to replicate our results and understand the mechanism.