Ethnic differences in umbilical cord blood vitamin D and parathyroid hormone--South Asians compared to Whites born in the UK.

Serum calcium, 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) were measured in umbilical cord blood samples taken from 54 White and 22 South Asian babies born in the UK during the summer months. South Asians had lower serum calcium (p < 0.0027) and 25OHD (p < 0.0002) than Whites. Serum PTH was low in all subjects, but South Asians had relatively higher concentrations of serum PTH (p < 0.001) than Whites. The lower vitamin D and calcium in South Asian newborns is not associated with secondary hyperparathyroidism as previously reported but may still explain their increased prevalence of neonatal hypocalcaemia and rickets.