The relative effects of fat versus muscle mass on cystatin C and estimates of renal function in healthy young men

BackgroundIt is well known that plasma creatinine concentration is affected by muscle mass, while some studies have suggested cystatin C is affected by body mass index (BMI). Our aim was to assess the effects of lean versus fat mass on cystatin C and creatinine derivative equations in estimating glomerular filtration rate (GFR) in healthy young men.MethodsThree groups of participants were studied: those classified as normal (BMI 18-25 kg/m 2 with body fat, 30%); muscular subjects (BMI .30 kg/m 2 and body fat, 20%); and obese subjects (BMI .30 kg/m 2 and body fat .30%). All underwent diethylenetriamine pentaacetic acid GFR, bio-electrical impedance and dual-energy X-ray absorptiometry body composition analysis, measurement of plasma cystatin C, creatinine and high-sensitivity C-reactive protein and completed a diet record.ResultsCystatin C was highest in the obese group (0.77 mg/L; 95% confidence intervals [CI] 0.69-0.77) and creatinine was highest in the muscular group (90.1 μmol/L; 95% CI 84.3-96.0). On ...