Urinary calcium excretion in a population of children living in Southern Italy

Background. Very few studies have evaluated the role of urinary calcium excretion as marker of bone metabolism in children. Normative data are lacking in these age groups. Methods. In a group of 122 children (66 females e 56 males), mean age 108.13±18.73 months, attending a primary school in Nocera Superiore (Southern Italy) the following parameters were evaluated: sex, age, weight, height, BMI (weight/height 2), urinary calcium excretion which was measured as the urinary calcium/creatinine concentration ratio (Uca/cr) in extemporaneous sample of the second urine in the morning. The Uca/cr ratio was not normally distributed in this childhood population. Natural logarithmic transformation was used to analyze the data. Results. The mean value of Uca/cr was 0.125±0.102 mg/mg. A significant correlation was found between the Uca/cr ratio and sex. The Uca/cr ratio values were higher in girls than in boys. Mean Uca/cr was 0.144±0.113 mg/mg in females while it was 0.102±0.083 mg/mg in males ("t"-test: p<0.05). No correlation was found between the Uca/cr ratio and other variables such as age, height, weight and BMI either in the simple or in the multiple linear regression analysis correcting both for the sex and the age. Data by age-group and sex were reported as percentile tables. Conclusions. The discussed variations of the Uca/cr in children from different areas and sex confirm the need for reference standards calculated in the different population groups.