Clinical aspects of vitamin D in the management of rheumatoid arthritis.

There is an increasing interest in the role of vitamin D as a potential treatment for a number of disparate diseases. In addition to its role in calcium homeostasis, vitamin D has a plethora of effects including immunomodulation, pleiotropic effects, modulating propensity to infection and blood pressure regulation. Detection and treatment of vitamin D deficiency in selected patients with RA is relevant as deficiency is common. Vitamin D therapy may modify the increased risk of falls and fracture in this group, and possibly exert additional immunomodulatory effects on disease onset and activity although data are largely epidemiological. Currently, there is no consensus view on vitamin D replacement regimens, nor an agreed optimal level of serum 25-hydroxyvitamin D [25(OH)D] for health. Indeed levels may vary for different organ systems and the concept of 'tissue specific vitamin D deficiency' needs to be considered. Therefore, there is clinical uncertainty regarding both when and how to correct vitamin D deficiency. Older patients, particularly post-menopausal women, and others at high risk of vitamin D deficiency should be preferentially targeted since they are likely to benefit most from supplementation. Clinicians should be aware of the technical difficulties associated with measuring and interpreting 25(OH)D levels. The administration of high-dose vitamin D as an oral weekly bolus is safe and can rapidly correct vitamin D deficiency followed by regular lower doses to maintain adequate levels.