Vitamin D status in children with latent tuberculosis infection and patients with tuberculosis

Introduction. Vitamin D plays an important role in anti-tuberculosis immunity, and the reduction level of this vitamin in the body is critical. Aim . To estimate the probability of diagnosis of active tuberculosis in children with positive ATR-test and/or IGRA test results and different vitamin D status. Materials and methods . A prospective study was conducted in 46 children aged 1–14 years from 2021 to 2023 in the Tuberculosis Department of St. Petersburg Children’s Infectious Diseases Hospital No. 3. Exclusion criteria comprised severe immunodeficiency diseases. The examination methods included the complex phthisiological examination and determination of serum calcidiol concentrations (inactive, main form of vitamin D). Results. 93.5% of the examined patients had low levels of this vitamin. The mean calcidiol level in all examined children was 14.60 ± 1.30 ng/ml. The clinical examination identified residual changes after earlier rickets in 80.4% of patients. Moreover, most children had normal blood macroelement concentrations: calcium – in 87.0%, phosphorus – in 67.4%, magnesium – in 84.8% of cases. The probability that active tuberculosis may be diagnosed in children with positive ATR-test and/or IGRA test results and vitamin D deficiency (level less than 20 ng/ml) was higher than in children with vitamin D deficiency and normal level (OR = 10.13 CI [2.32–44.17] Se = 0.75, RR = 2.66 CI [1.16–6.10] Se = 0.42; F = 0.0017; χ 2 = 11.060 (p < 0.001); φc = 0.49). Among children with vitamin D deficiency (level less than 20 ng/ml) and active tuberculosis, the proportion of complicated and disseminated forms was 48.1%, while among children with vitamin D deficiency and normal concentration, it was not observed. Discussion. The mean calcidiol level in all examined children was 14.60 ± 1.30 ng/ml, which indicated the absence of active manifestations of rickets during examination, and therefore the prevalence of decreased immune system function due to vitamin D insufficiency. Conclusions. Vitamin D deficiency is a significant endogenous factor contributing to the development of tuberculosis.