Urinary uric acid : creatinine ratios in healthy Turkish children.

BACKGROUND: Determining uric acid : creatinine ratios in random urine samples may be useful to assess the excretion of uric acid in children. Because it was shown that urinary uric acid excretion varies with age and geographic area, it is important to have accurate reference values of uric acid excretion. The aim of the present study was therefore to obtain regional reference values for urinary uric acid : creatinine ratios in healthy Turkish children. METHODS: A total of 1306 children aged 1 month-15 years were analyzed for uric acid and creatinine, and urinary uric acid : creatinine ratios were determined from each sample. The second non-fasting morning urine samples were taken from all the children. Urine samples were analyzed for uric acid using the uricase method, and for creatinine with the Jaffe reaction. RESULTS: The mean +/- SD and 5th-95th percentiles of urinary uric acid : creatinine ratios (mg/mg) were 1.09 +/- 0.48 and 0.27-1.87 at 1-6 months, 0.86 +/- 0.41 and 0.19-1.64 at 7-12 months, 0.76 +/- 0.32 and 0.32-1.43 at 1-3 years, 0.63 +/- 0.29 and 0.20-1.23 at 4-6 years, 0.44 +/- 0.24 and 0.14-0.93 at 7-11 years, and 0.30 +/- 0.14 and 0.12-0.62 at 12-15 years. Uric acid : creatinine ratios were not significantly different between boys and the girls except at 12-15 years. Girls aged 12-15 years had higher urinary uric acid : creatinine ratio when compared with boys (P < 0.05). There was no correlation between urinary uric acid : creatinine ratio and protein intake. CONCLUSIONS: Urinary uric acid : creatinine ratio changes with age. When assessing urinary uric acid : creatinine ratio, the clinician should consider the age of the child.