Vitamin D2 treatment for vitamin D deficiency and insufficiency for up to 6 years.

T he worldwide prevalence of vitamin D deficiency is striking, and more than 40% of the population may be vitamin D deficient. Despite this, to our knowledge there are no long-term studies of the safety and efficacy of giving pharmacologic doses of vitamin D (50 000 IU of ergocalciferol [vitamin D2]) to treat and prevent vitamin D deficiency. Furthermore, there is a concern that ergocalciferol, the only pharmaceutical vitamin D available in the United States, may be less effective than cholecalciferol (vitamin D3). In our clinic, which specializes in metabolic bone disease, we routinely treat vitamin D deficiency (serum 25hydroxyvitamin D [25(OH)D] levels 20 ng/mL [to convert to nanomoles per liter, multiply by 2.496]) with 50 000 IU of ergocalciferol once a week for 8 weeks. The efficacy of this regimen has been previously described. To prevent recurrent vitamin D deficiency and also to maintain adequate levels in patients who are vitamin D sufficient, we treat with 50 000 IU of ergocalciferol every other week indefinitely, a regimen that, to our knowledge, has not been published to date.