Declining renal function and thresholds of estimated glomerular filtration rate: impact on biomarkers of oxidative stress in the BIOCLAIMS cohort

Impaired glomerular filtration rate (eGFR) is frequently observed in apparently healthy individuals, and even slightly and mildly impaired renal function may have an impact on metabolic health. The aim of this study was to investigate the effects of declining eGFR (MDRD formula) and identify possible thresholds of eGFR on biomarkers of oxidative stress and antioxidant status. In a cross-sectional study, 1310 study subjects, 606 F, 704 M, 18-85 years (BIOCLAIMS cohort), were enrolled for biomarker analysis, including plasma human mercaptalbumin (HMA) (HPLC), activation of NF-kB in PBMC (TransAM Active Motif assay), and plasma total peroxides (TOC assay, LDN), as well as plasma ascorbate, α- and g-tocopherol, and different carotenoids (HPLC), and grouped for eGFR (>90, 75-90, 60-75, 45-60, 30-45 ml/min/1.73 m2). Results showed eGFR-related significant differences already at 75 ml/min/1.73 m2 for plasma total peroxides; at 60 ml/min/1.73 m2 for plasma HMA, PBMC NF-kB p50 subunit as well as for plasma ascorbate, f3-cryptoxanthin, lutein/zeaxanthin, f3-carotene; and for all of the above further at 45 ml/min/1.73m2 (all P