Background: This study was performed in an attempt to assess serum calcium, phosphorus, and alkaline phosphatase in adolescent girls and calcium supplementation in subjects with abnormal serum findings.
Methods: A randomized, cross-sectional, cluster sampling, prospective, and descriptive trial was conducted from January through March 2003 for measurement of serum calcium, phosphorus, and alkaline phosphatase. The study group consisted of healthy girl students aged 11 – 15 years, from various areas of Tehran, Iran. Supplementary calcium tablets (2000 mg per day) were prescribed for 20 days for girls with low or normal serum calcium and raised alkaline phosphatase concentration. Results: Of 414 girls who were evaluated, 29 (7%) had low or normal serum calcium and raised alkaline phosphatase concentration, with other normal findings. The mean serum calcium and alkaline phosphatase in these girls were 9.4 ± 0.4 mg% and 1168 ± 156 IU/L, respectively. The mean serum calcium in 8 (27.58%) of these 29 girls were 8.02 ± 0.3 mg%. The serum calcium and alkaline phosphatase after calcium supplementation were 9.6 ± 0.9 mg% and 666 ± 310 IU/L, respectively, with a significant (P < 0.05) difference existing in serum alkaline phosphatase concentration among girls before and after supplementation. The serum phosphorus concentration in all girls was normal.
Conclusion: Hypocalcemia is common in adolescent girls, which is among the subtle biochemical findings of rickets during the rapid growth period and may progress into symptomatic rickets.