Values of Urinary Mineral Excretion in Healthy Iranian Children

Normal values of urinary mineral excretion differ in different geographic parts. The aim of this study was to determine age-related reference intervals for urinary minerals in healthy children in the south-west of Iran. Midstream non-fasting urine samples were collected and the amount of calcium, oxalate, uric acid, phosphate, magnesium, citrate, and creatinine was measured in all urine samples. The urinary mineral concentrations were reported as mineral to creatinine ratios (mg/mg). Data were analyzed by SPSS software version 16 and independent t-test and T-Hoteling test was used. The study involved 232 children aged 7 to 10 years. The 5th and 95th percentile values of urinary minerals to creatinine ratios were determined. The mean urinary Ca/Cr ratio was 0.14± 0.18 with a 95th percentile value of 0.295. For oxalate to creatinine ratio, the mean value was 0.068± 0.09 mg/mg with a 95th percentile value of 0.23. The mean uric acid to creatinine ratio was 0.358±0.211 mg/mg with an upper 95th percentile value of 0.69 and the mean Ph/Cr ratio was 0.439 and the 95th percentile was 1.01 mg/mg. We found out that the normal values of random urinary mineral to creatinine ratio differ in our region from the other countries and even from the other regions in Iran. We concluded that child''s age and ethnicity should be taken into consideration when assessing the urinary mineral to creatinine ratio.