CYP24A1 and vitamin D deficiency: We propose that primary calcium deficiency in Nigerian children induces an increase in 1α-hydroxylase activity that, combined with increased activity of degradative pathways (eg, CYP24), results in a state of relative vitamin D deficiency.(12) Based on a growing body of evidence, it is likely that reduced serum levels of 25(OH)D have an independent and adverse effect on bone and mineral metabolism in these children, leading both to increased secretion of PTH(23,24) and impaired bone mineralization.(25)