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

To determine the efficacy of supplementation with oral vitamin D3 (cholecalciferol) on bone mineral biochemical parameters of school-going girls. Government school (government-aided) and Private school (fee paying) in Delhi. Randomized controlled trial. 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. 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). Serum 25(OH)D, calcium, phosphorus, parathyroid hormone, and alkaline phosphatase levels at 6 and 12 months after start of supplementation. 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, twomonthly 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. 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.