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.