Reference Values for Serum Creatinine with Jaffe-compensated Assay in Adult Iranian Subjects: Tehran Lipid and Glucose Study

BACKGROUND: Chronic kidney disease is a worldwide public health problem and glomerular filtration rate (GFR), the best overall index of renal function, is most commonly estimated from serum creatinine concentrations. The aim of this study was to determine reference values for serum creatinine concentrations using data from a population-based study in Iran. METHODS: Serum creatinine was measured using the Jaffe method in 5247 men and women, aged 20–88 years, participants of the Tehran Lipid and Glucose Study. For calculating Jaffe compensated creatinine values in 382 samples, it was measured using both the Jaffe and the enzymatic p-aminophenazone (PAP) methods. Linear regression analysis yielded a regression line equation of Jaffe-creatinine=0.863 × PAP-creatinine + 38.9 μmol/L (r = 0.973, n = 382, P < 0.001). CLSI/IFCC guidelines (International Federation of Clinical Chemistry/ Clinical and Laboratory Standards Institute), non-parametric method was used for determining creatinine reference values. RESULTS: Reference values for serum creatinine ranged between 47–98 μmol/L (0.53–1.11 mg/dL), 37–68 μmol/L (0.42–0.77 mg/dL), and 37–78 μmol/L (0.42–0.88 mg/dL) in men, non-menopausal women, and menopausal women, respectively. Mean serum creatinine concentration was significantly higher in men compared to women for both age ≤ 50 years [70 ± 11 vs. 50 ± 10 μmol/L (0.79 ± 0.12 vs. 0.57 ± 0.11 mg/dL), P < 0.001] and age > 50 years [73 ± 12 vs. 55 ± 12 μmol/L (0.83 ± 0.14 vs. 0.62 ± 0.14 mg/dL), P < 0.001]. CONCLUSION: Reference values for serum creatinine using the compensated Jaffe method are presented in Iranian subjects, which may help with assessment of kidney function.