Objective Urolithiasis is a common disorder that involves the kidney, but the pathogenesis of hypercalciuria and its relation with urolithiasis has not yet been completely determined. In this study we will try to answer the question: is there any relation between parent urinary stones and the rate of hypercalciuria in their siblings?

Methods This is a prospective and case–control study on 70 children who have been established with urinary stones in their close family (father or mother). The first group was compared with another of the same age, sex, equal diet and not using drugs as a control group. Hypercalciuria is defined as a urinary calcium to creatinine ratio of more than 0.2. This study was done in Zanjan city (Iran) in summer 2007. We tried to eradicate the factors that influence calcium excretion. Both groups were the same age (8–13 years) and the male/female ratio was equal. After taking an exact medical history and filling in the special form by questionnaire, a fresh fasting urine sample was taken in the early morning. We checked the urinary calcium/creatinine ratio by one laboratory. Finally, we analysed, evaluated and compared the results with the cooperation of our consultants.

Results From 70 children of the first group, 31 cases (44%) had hypercalciuria; 16 and 15 of them were girls and boys, respectively. On the other hand, in the control group we found only 16 cases (22%) of hypercalciuria (p<0.05). In this group the male/female ratio was also equal (8/8).

Conclusions The present study showed that there is a positive relation between family urolithiasis and hypercalciuria in their children, so in a high incidence of urolithiasis area, searching for childhood hypercalciuria is highly recommended. It seems that further research in this field is necessary.