Introduction: Epidemiological evidence suggests that vitamin D (25(OH)D3) deficiency is an acquired risk factor for tuberculosis (TB). Lack of sunshine during the winter reduces 25(OH)D3 levels markedly, but darker skin pigmentation reduces 25(OH)D3 synthesis in African and Asian populations wherever they live.
Aims: To examine 25(OH)D3 deficiency and its associations in TB patients in a regional population.
Methods: Serum 25(OH)D3 concentrations were measured pre-treatment in patients with active TB, from January 2006 to September 2007. Prevalence of 25(OH)D3 deficiency and its relation to ethnic origin, skin colour, site of TB, duration in the UK, month of 25(OH)D3 estimation were determined.
Results: One hundred and fifty eight patients (13 UK-born) were identified (71 female, 87 male). Mean age was 32(S.D.+14). Only 11(7%) had adequate 25(OH)D3 levels.
Of 61 Black patients, 2 had adequate 25(OH)D3 levels, 34 were insufficient, 25 were deficient. Of 87 Asian patients (60 Indian, 4 Pakistani, 2 Sri Lankan, 2 Bangladeshi, 2 Afghani), 7 had adequate 25(OH)D3 levels, 47 were insufficient, 33 were deficient. Of 4 White patients, 1 had adequate 25(OD)D3 levels, 2 were insufficient, 1 was deficient. Of 6 other patients (1 Nepalese, 2 Pilipino, 2 Brazilian, 1 Chinese), none had adequate 25(OH)D3 levels.
There was no association between serum concentrations of 25(OH)D3 and skin pigmentation, site of TB or duration of residence in the UK. There was no apparent seasonal variation in either TB diagnosis or 25(OH)D3 level. The expected rise of 25(OH)D3 to peak concentrations in the summer months was absent in our TB population. Of 20 patients with TB drug resistance only 1 had adequate 25(OH)D3 levels.
Conclusion: Patients with active TB have low serum 25(OH)D3 concentrations and do not show the expected seasonal variation. Possible abnormal handling of the vitamin may contribute to that. Clinical trials may help determine whether 25(OH)D3 supplementation prevents reactivation of latent TB infection.