Vitamin D and bone mineral density status of healthy schoolchildren in northern India

Abstract

Background: Current data on the prevalence of vitamin D deficiency in India are scarce. Objective: We assessed the calcium-vitamin D-parathyroid hormone axis in apparently healthy children from 2 different socioeconomic backgrounds in New Delhi, India. Design: Clinical evaluation for evidence of vitamin D deficiency was carried out in 5137 apparently healthy schoolchildren, aged 10–18 y, attending lower (LSES) and upper (USES) socioeconomic status schools. Serum calcium, inorganic phosphorus, alkaline phosphatase, 25-hydroxyvitamin D [25(OH)D] and immunoreactive parathyroid hormone were measured in 760 children randomly selected from the larger cohort. Bone mineral density of the forearm and the calcaneum was measured in 555 children by using peripheral dual-energy X-ray absorptiometry. Results: Clinical evidence of vitamin D deficiency was noted in 10.8% of the children. Children in the LSES group had a significantly (P < 0.01) lower 25(OH)D concentration (10.4 ± 0.4 ng/mL) than did those in the USES group (13.7 ± 0.4 ng/mL). Concentrations of 25(OH)D <9 ng/mL were seen in 35.7% of the children (42.3% in LSES; 27% in USES; P < 0.01). Boys had significantly (P = 0.004) higher 25(OH)D concentrations than did girls. There was a significant negative correlation between the mean serum immunoreactive parathyroid hormone and 25(OH) D concentrations (r = −0.202, P < 0.001). Mean forearm bone mineral density was significantly (P < 0.01) higher in the USES group than in the LSES group. Conclusion: A high prevalence of clinical and biochemical hypovitaminosis D exists in apparently healthy schoolchildren in northern India.