Serum Cystatin C Levels in Nigerian Children: Reference Intervals and Relationship to Demographic and Anthropometric Variables

BACKGROUND: Cystatin C has been recognized as a good marker of kidney function but reference ranges have not been determined in Nigerian children. OBJECTIVE: To determine the reference range of serum cystatin C in Nigerian children with no overt signs of kidney disease and to determine and compare the relationship of serum cystatin C and serum creatinine with demographic and anthropometric variables. METHODS: Fifty-nine children aged two years to 16 years with no evidence of overt kidney disease were recruited from the Paediatric Clinics of the Lagos University Teaching Hospital. Serum cystatin C levels were measured using ELISA method while serum creatinine was measured by a rateblanked and compensated Jaffe method using a Roche/Hitachi 902 auto-analyser. Both were measured using the same serum sample. RESULTS: The mean (±1.96SD) serum cystatin C level was 0.73 (0.41–1.04) mg/L and was similar among male and female children (P=0.640) and between children younger than five years and those five years and older (P=0.596). Unlike cystatin C, serum creatinine was higher among children five years or older. In contrast to serum creatinine, serum cystatin showed no significant correlation with age (r=0.153, P=0.246), weight (r=0.062, P=0.641) and length (r=0.067, P=0.612). CONCLUSION: Serum cystatin C reference range in Nigerian children is similar to that reported for children in other regions of the world and appears to be independent of gender, weight, height, body mass index and age after two years