Reference serum cystatin C levels in Japanese children

Single measurements of serum cystatin C (cysC) concentration have generally been used to determine glomerular filtration rate (GFR) in adults. Since GFR varies to some extent among children, we attempted to determine reference serum cysC concentrations for Japanese children. Serum cysC concentrations were determined by a latex particle-enhanced turbidimetric immunoassay in children who did not present with kidney disease or infectious disease, and the relationship between age and serum cysC level was assessed. We found that reference serum cysC levels gradually decreased during the first year after birth, thereafter becoming constant. Mean serum cysC concentration in children aged 1 year (0.76 +/- A 0.10 mg/L) was slightly higher than in children aged a parts per thousand yen2 years (0.70 +/- A 0.09 mg/L). Our reference values will be applicable for screening renal function in Japanese children.