Overweight, Obesity, and Elevated Serum Cystatin C Levels in Adults in the United States

BackgroundAlthough high body mass index (BMI) is a risk factor for hypertension, diabetes, and cardiovascular disease, limited data exist on the association of overweight and obesity with early stages of kidney disease.MethodsCross-sectional data for 5083 participants of the nationally representative Third National Health and Nutrition Examination Survey with an estimated glomerular filtration rate ≥ 60 mL/min/1.73 m2 without micro- or macroalbuminuria were analyzed to determine the association between BMI and elevated serum cystatin C. Normal weight, overweight, class I obesity, and class II to III obesity were defined as a BMI of 18.5 to 24.9 kg/m2, 25.0 to 29.9 kg/m2, 30.0 to 34.9 kg/m2, and ≥ 35.0 kg/m2, respectively. Elevated serum cystatin C was defined as ≥ 1.09 mg/L (≥99th percentile for participants 20-39 years of age without diabetes, hypertension, micro- or macroalbuminuria, or stage 3-5 chronic kidney disease).ResultsThe age-standardized prevalence of elevated serum cystatin C was 9.6%, 12.9%, 17.4%, and 21.5% among adults of normal weight, overweight, class I obesity, and class II to III obesity, respectively (P trend < .001). After multivariate adjustment for demographics, behaviors, systolic blood pressure, and serum biomarkers, and compared with participants of normal weight, the odds ratio (95% confidence interval) of elevated serum cystatin C was 1.46 (1.02-2.10) for overweight, 2.36 (1.56-3.57) for class I obesity, and 2.82 (1.56-5.11) for class II to III obesity.ConclusionA graded association exists between higher BMI and elevated serum cystatin C. Further research is warranted to assess whether reducing BMI favorably affects elevated serum cystatin C and the development of chronic kidney disease.