Serum cystatin-C values in children by age and their fluctuation duringdehydration

BACKGROUND: Serum creatinine level (Cr) is extensively used as an index of glomerular filtration rate (GFR) with bedside patients. As serum Cr level differ by the muscle volume, the use of serum Cr as an index of GFR has long been considered problematic in children. METHODS: The subjects of this study were 135 healthy children aged from 1 to 15-years-old. As a pathological condition, the changes in serum cystatin C (Cys-C) in the children whose blood urea nitrogen exceeded 20 mg/dL during the acute stage of dehydration were also investigated. RESULTS: The mean serum Cys-C value was 0.67 +/- 0.19 mg/L on the whole. There was not any male-female difference. The mean serum Cys-C values of the 12 cases in the acute stage and the recovery stage were 0.61 +/- 0.12 mg/L and 0.64 +/- 0.14 mg/L, respectively, indicating no significant difference. CONCLUSION: Serum Cys-C is considered as a favorable index of GFR in children because it is not influenced by age and sex. As it is not influenced by the prerenal factors either, serum Cys-C is useful in children over 1-years-old.