Impact of two regimens of vitamin D supplementation on calcium - vitamin D - PTH axis of schoolgirls of Delhi.

OBJECTIVE To determine the efficacy of supplementation with oral vitamin D₃ (cholecalciferol) on bone mineral biochemical parameters of school-going girls. SETTING Government school (government-aided) and Private school (fee paying) in Delhi. DESIGN Randomized controlled trial. INTERVENTION Cholecalciferol granules (60,000 IU) orally with water, either once in two months (two-monthly D₃ group) or once a month (one-monthly D₃ group) for one year. PARTICIPANTS 290 healthy schoolgirls (6-17 y), 124 from lower socioeconomic strata (LSES) (attending government schools) and 166 from upper socioeconomic strata (USES) (attending private schools). OUTCOME MEASURES Serum 25(OH)D, calcium, phosphorus, parathyroid hormone, and alkaline phosphatase levels at 6 and 12 months after start of supplementation. RESULTS At baseline, 93.7% schoolgirls were vitamin D deficient [25(OH)D<50 nmol/L]. While significant increase in serum calcium and decrease in alkaline phosphatase levels was noted in both groups with both interventions, PTH response was inconsistent. In LSES subjects, two-monthly D₃ and one-monthly D₃ supplementation resulted in a significant increase in serum 25(OH)D levels by 8.3 nmol/L and 11.0 nmol/L, respectively at 6 months (P<0.05). Similarly, the increase in the two intervention arms in USES subjects was 10.5 nmol/L and 16.0 nmol/L, respectively (P<0.05). In both groups, this increase in serum 25(OH)D levels persisted at 12 months (P<0.05). Despite supplementation with 60,000 IU of Vitamin D₃ (monthly or two-monthly), only 47% were vitamin D sufficient at the end of one year. CONCLUSIONS 60,000 IU of cholecalciferol, monthly or two-monthly, resulted in a significant increase in serum 25(OH)D levels in vitamin D deficient schoolgirls.