Does vitamin D improve the serum level of anti-TPO and anti-TG in Autoimmune thyroid diseases? A systematic review and meta-analysis

Accumulating evidence suggests vitamin D play a role in autoimmune diseases. However, at this time the finding on its role in autoimmune and thyroid disease is not conclusive. Then, we aimed to review and update data on the effectiveness of vitamin D on thyroid auto antibodies, anti-TPO and anti-TG in adults.

Scopus and PubMed search engines were used up to February 2018 for clinical trials without any restriction in time and language. The outcome parameters were thyroid auto antibodies, anti-TPO and anti-TG. We included studies which reported aim parameters. Results were summarized as mean differences (MD) with 95% confidence intervals (CI). Effect sizes were pooled using random-effects models (the DerSimonian-Laird estimator).

Eight trials involving 526 subjects were included in this meta-analysis. Vitamin D supplementation did not significantly changed the serum level of anti-TPO (MD: -46.901 IU/mL, 95% CI: -111.841, 18.039, p=0.157) and anti-TG (MD: -0.903 IU/mL, 95% CI: -2.208, 0.401, p = 0.175) with high heterogeneity (I2= 77.1%, p= 0.000, I2= 26.5%, p= 0.253). Anti-TPO reduction was considerable in mixed-sex and low quality trials, doses of ≥ 1000 IU, periods of ≥ 2 months , AITD patients and in subjects with lower initial serum levels of vitamin D and higher initial serum level of anti-TPO (p

Vitamin D supplementation did not improve the serum levels of anti-TPO and anti-TG. The effects of vitamin D supplementing on AITD should be further investigated by conducting larger sample size and well-defined trials of long enough duration.