Severe hypovitaminosis D in active tuberculosis patients and its predictors

Tuberculosis (TB) patients have a significant vitamin D deficiency (VDD) endemic, which may be closely related to the onset and progress of the disease. The comorbidity of diabetes (DM) and TB has posed an increasing challenge in recent years. However, the influence of DM on TB and the possible mechanism are still uncertain. We carried out this study to identify the nutritional status of vitamin D (VD) in TB patients in a northern city in China (latitude 36° N) and investigate the possible predictors of severe vitamin D deficiency (SVDD).

A cross-sectional study including 461 active TB patients (192 with and 269 without DM) were randomly selected from Qingdao Chest Hospital from June 2015 to August 2016. We measured serum 25 hydroxyvitamin D [25(OH)D], and investigated the association between sociodemographic, dietary intake, DM, body mass index (BMI), severity of initial TB signs and symptoms (TB score) and VD status. Multivariate logistic regression analysis was used to define the possible predictors of SVDD.

The median serum 25(OH)D concentration was 8.50 ng/mL. Of the 461 TB patients included, 383 (83.1%) had VDD [25(OH)D < 20 ng/mL], and 217 (47.1%) had SVDD [25(OH)D < 8 ng/mL]. The variables associated with serum 25(OH)D concentrations were DM, outdoor activity level, TB score and BMI (p < 0.05). Patients with severe TB score had nearly 5 fold higher risk of having SVDD compared with those in mild subgroup [OR (95% CI) = 4.919 (2.644-9.150), p < 0.001]. Low outdoor activity level also increased the odds of SVDD, while DM and high fish consumption showed protect effects.

Severe hypovitaminosis D is prevalent in active TB patients, and the main predictors of SVDD were severe TB score, low outdoor activity, inadequate fish consumption. Lowered serum 25(OH)D may be associated with increased risk of TB in DM.