Kidney function and markers of inflammation in elderly persons without chronic kidney disease: The health, aging, and body composition study

Inflammatory markers are elevated in persons with estimated glomerular filtration rates less than 60 ml/min/1.73 m2. As cystatin C may detect small changes in kidney function not detected by estimated glomerular filtration rate, we evaluated the association between cystatin C and serum markers of inflammation in older adults with estimated glomerular filtration rate ≥60. This is an analysis using measures from the Health, Aging, and Body Composition Study, a cohort of well-functioning adults aged 70–79 years. Cystatin C correlated with all five inflammatory biomarkers: C-reactive protein (r=0.08), interleukin-6 (r=0.19), tumor necrosis factor α (TNF-α) (r=0.41), soluble TNF receptor 1 (STNF-R1) (r=0.61), and soluble TNF receptor 2 (STNF-R2) (r=0.54); P<0.0005 for all. In adjusted analyses, cystatin C concentrations appeared to have stronger associations with each biomarker compared with estimated glomerular filtration rate or serum creatinine. Participants with a cystatin C≥1.0 mg/l had significantly higher levels of all five biomarkers compared to those with a cystatin C<1.0 (mean differences ranging 16–29%, all P<0.05). Cystatin C has a linear association with inflammatory biomarkers in an ambulatory elderly cohort with estimated glomerular filtration rates ≥60; associations are particularly strong with TNF-α and the STNF-R.