Pediatric Reference Values for Serum Creatinine and Estimated Glomerular Filtration Rate in Iranians: Tehran Lipid and Glucose Study

BACKGROUND: Serum creatinine is the most widely used marker for estimating glomerular filtration rate (GFR). The aim of this study was to determine pediatric reference values for serum creatinine levels and eGFR values using data from a population-based study in Iran. METHODS: Serum creatinine of 1594 subjects, aged 3 – 18 years, participating in phase 4 of the Tehran Lipid and Glucose Study (2008 – 2011) was measured using the conventional Jaffe method. The non-parametric method of Schwartz and Counahan-Barratt equations were used to calculate eGFR. CLSI/IFCC guidelines were used to determine reference values. RESULTS: In both genders, serum creatinine concentration was significantly increased with age and had a positive correlation with age (boys (r = 0.786, n = 778, P < 0.001) and girls (r = 0.638, n = 724, P < 0.001)). In addition, mean serum creatinine concentration was significantly higher in boys, compared to girls (0.86 ± 0.01 vs. 0.80 ± 0.01 mg/dL, P < 0.001). Based on these results, we proposed the following formula: serum creatinine (mg/dL) = k × age (year) + 0.5, where k was 0.03 for boys and 0.02 for girls. CONCLUSIONS: This study presents pediatric reference values in Iranian boys and girls for serum creatinine levels to be 0.6 – 1.20 mg/dL and 0.6 – 1.00 mg/dL and for eGFR values to be 81 – 154 mL/min/1.73 m2 and 80 – 129 mL/min/1.73 m2, respectively. These values can be used for diagnostic and therapeutic purposes.