Urinary Calcium Excretion in Healthy Children Living in Kashan/ Iran

Objective: Urinary calcium excretion is different in various geographical regions. Therefore, we decided to evaluate the urinary calcium excretion in pediatric inhabitants of residential districts in the Desert of Iran and to determine the frequency of hypercalciuria.
Methods: This study was carried out from 2004 to 2005 on healthy children aged 7-12 years in Kashan (Central Desert of Iran). By proportional cluster sampling 95 rural and 305 urban cases were selected. The second non fasting morning urine sample was collected for measuring sodium, creatinine and calcium. Children whose urine calcium to creatinine ratio was more than 0.2 and urine sodium more than 200 meq/l were considered as hypercalciuric and hypernatriuric. Water samples were collected by health worker from 9 regions of the city and 9 villages for chemical analysis. The differences between frequencies were assessed by chi square test. P values less than 0.05 were considered significant.
Findings: A total of 362 (175 females, 187 males) with a mean age of 9.5 (±1.4) years were studied. Mean urinary calcium/creatinine concentration ratio was 0.2 (±0.17). The 95th percentile value for urine calcium/creatinine concentration was 0.53 and prevalence of hypercalciuria was found as 37.8%. The contents of water were similar in Kashan city and the villages, only the mean of total water density was higher in water supply of the city (P<0.05). By regression analysis we found only direct but weak correlation between urine calcium and urine sodium excretion (r=0.37, P=0.0001).
Conclusion: Urinary calcium excretion is high in desert of Kashan; thus it is important to conduct more studies to determine the risk factors and its untoward effect such as nephrolithiasis.

Keywords
Hypercalciuria, Urine sodium, Hematuria, Urolithiasis, School aged children