Myasthenia Gravis and Vitamin D Serum Levels: A Systematic Review and Meta-analysis

Background: Vitamin D has been extensively studied for its role in immune modulation, especially in the process of tolerance induction. The loss of tolerance towards self-antigens is the basis of several autoimmune disorders; this seems to be related to lower levels of Vitamin D. A neurological autoimmune disorder due to the loss of tolerance to compounds at the neuromuscular junction is known as Myasthenia Gravis (MG). Objective: To assess the possible correlation between altered Vitamin D levels and MG. Methods: In this systematic review, all recruited studies compared Vitamin D levels in MG patients and healthy controls. Five studies fulfilled the selection criteria and were included in the quantitative synthesis. The meta-analysis involved data of a total population size of 450 individuals, equally divided into 219 cases and 231 controls. Results: The results showed a statistically significant mean difference between cases and controls. The overall mean Vitamin D levels in MG patients were 4.69 ng/ml lower than control levels (95% CI -6.17; -3.22); by applying a random-effects model, this mean difference was estimated at -3.79 (95% CI -7.24; -0.33), after exclusion of data source of heterogeneity and through applying a fixed-effect model, resulted in a mean difference -5.39 (95% CI -6.91; -3.88). The p-value was lower than 0.05. Conclusion: There are statistically significant lower levels of Vitamin D in MG patients, so routine checking and possible correction should be advised in MG patients based on the current data.