Vitamin D Deficiency in the Pediatric Tuberculosis Clinic in Winnipeg, Manitoba

Abstract

Background: Vitamin D (VD) plays an important role in inflammatory and immune reactions and may be critical in the human response to tuberculosis (TB). With the increased prevalence of TB in the aboriginal (A) population, especially those residing in Northern Manitoba (NM) we sought to identify how frequently children seen in the TB Clinic were VD deficient (VDD). Methods: VD levels were drawn (as part of routine baseline blood work as per clinic protocol) from patients referred to the TB clinic for contact investigation, school/immigration screening or treatment of primary/pulmonary /disseminated disease beginning July 1, 2006. VD levels to June 2008 were evaluated. The normal reference value used was 75-250 nmol/L. VD insufficiency (VDI) was when the level was 25-75 nmol/L and VDD was diagnosed in those with levels <25 nmol/L. The incidence of VDD was assessed and related to age, sex, diagnosis, place of residence, timing of blood draw and ethnicity. Results: Three hundred sixty-four (80% A) children had blood levels drawn during the 24-month period. Four hundred twenty-four specimen were processed - 26% VDD, 63% VDI and 11% with normal VD levels. Twenty-eight percent of A patients residing in NM were VDD. Nineteen percent of immigrants were VDD. Only 20% of children <4 years of age had normal VD while 49% of those >15 years were VDD. Timing of blood draw (season) did not affect the distribution of levels. Twenty-six percent of children with latent TB infection, 39% of patients with primary disease, 60% with pulmonary disease and 25% of those with disseminated disease were VDD. Conclusion: VDD is common in A children. What role and contribution genetics, diet and environment play require further study, especially as to whether the prevention of VDD may reduce the risk of developing TB.