[Urinary calcium, magnesium and uric acid in normal children]

In a group of 327 normal children, aged 4 to 11, we measured Calcium (Ca) and Creatinine (Cr) in the second morning urine. In 226 of them, Magnesium (Mg) and Uric Acid (UA) were also calculated. Means and SD were respectively Ca/Cr: 0.11 +/- 0.09, Mg/Cr: 0.10 +/- 0.03, Mg/Ca: 1.56 +/- 1.48 and UA/Cr: 0.093 +/- 0.29. Distribution was not normal, so we used the 97.5 centile for the upper acceptable limit. This value was higher for Ca/Cr (0.37) and different for Mg/Cr (0.17), compared to the previous reports. Our values of Mg/Ca were related to age (p less than 0.01). These results suggest the need for local establishment of normal ranges and a better definition of hypercalciuria and hypermagnesiuria.