Cystatin C a marker for renal function after exercise.

Renal impairment is common during and after severe exercise. In clinical practice, renal function is evaluated using serum creatinine, urine parameters, and equations to estimate the Glomular Filtration Rate (GFR). However, creatinine levels may be biased by skeletal muscle damage and the GFR equations, requiring age, gender and body weight, are shown to be inadequate in normals. In the present study, we show that serum cystatin C and creatinine concentrations were elevated after marathon running in 26% and 46% of the 70 recreational male runners, respectively, possibly because of reduction in renal blood flow. The mean cystatin C increase was twice as low as compared to creatinine (21% and 41%, respectively), suggesting that cystatin C is indeed less biased by muscle damage. Future research has to reveal whether training diminishes the elevation in renal markers. Overall, cystatin C seems a more reliable method to establish renal function during and after extensive exercise. Georg Thieme Verlag KG Stuttgart.