URINARY CALCIUM EXCRETION IN CHINESE ADOLESCENTS

Objectives: To obtain normative reference values for urinary calcium e xcretion in Chinese adolescents. Methodology: A random group of 425 he althy Chinese adolescents aged 12-19 years were recruited from seconda ry schools in Hong Kong, Each subject provided a sample of morning uri ne for the assessment of calcium and creatinine excretion. A subgroup of 80 subjects provided a 24-h urine sample for assessment of daily ca lcium excretion. Results: The mean (+/-S.D.) and median urinary calciu m/creatinine concentration ratios (UCa/Cr) expressed in mmolmmol creat inine were 0.18 (+/- 0.16) and 0.12. Girls had a higher UCa/Cr than bo ys (P < 0.0001). The mean +/- S.D. 24-h urinary calcium excretion was 0.043 +/-0.025mmol kg day(-1) (1.71 +/- 1.01 mg kg day(-1)). Conclusio n: The UCa/Cr ratio and 24-h urinary calcium excretion are low when co mpared with published values for Caucasian children. The apparent rari ty of nephrolithiasis and microscopic haematuria associated with hyper calciuria may be related to the low urinary calcium excretion in this population.