Vitamin D(3) Concentration Correlates with the Severity of Multiple Sclerosis

BACKGROUND: To investigate the possible association between serum 25(OH) vitamin D(3) concentration and the severity of disease in Iranian patients with multiple sclerosis (MS) and to compare this concentration with a matched control group. METHODS: This was an analytical cross-sectional study performed at Jondishapour Neurology Clinic in Tehran, Iran. Patients with relapsing–remitting MS were categorized by disease severity: mild [0≤ Expanded Disability Status Scale (EDSS) ≤3], moderate (3.5≤EDSS≤5.5), and severe (6≤EDSS). Serum concentrations of 25(OH) vitamin D(3), calcium, phosphorus, magnesium, and parathyroid hormone were measured in 98 MS patients and 17 healthy age- and sex-matched controls. Fisher's exact, Kruskal–Wallis, Mann–Whitney U test, and independent t and Spearman rank correlation tests were used. RESULTS: Serum 25(OH) vitamin D(3) concentration was significantly lower in patients with MS, especially in the severe MS subgroup, compared with healthy controls (P=0.047). There was a statistically significant inverse correlation between 25(OH) vitamin D(3) concentration and EDSS score (P=0.049, R=−0.168 by Spearman rank correlation test), which was observed in women only (P=0.044, R=−0.199). CONCLUSIONS: Our findings not only further disclose the lower level of vitamin D in MS patients in comparison with healthy controls, but also support the association between vitamin D and disease severity in MS.