association of serum 25(oh) vitamin d3 concentration with severity of multiple sclerosis.

background: there is a known inverse association between solar radiation and the prevalence of multiple sclerosis (ms). some studies have investigated the link between vitamin d and ms. the aim of this study was to investigate the possible association between serum 25(oh) vitamin d3 concentration and the severity of disease in iranian patients with ms. methods: patients with relapsing-remitting ms underwent neurological examination, including measurement of expanded disability status scale (edss) score, and were categorized by disease severity into mild (0 ≤ edss ≤3), moderate (3.5 ≤ edss ≤5.5) and severe (6 ≤ edss). serum concentrations of 25(oh) vitamin d3, calcium, phosphorus, magnesium and parathyroid hormone were also measured. results: a total of 78 (73.1% female) patients with ms were evaluated. the mean (± standard deviation) of age was 33.9 ± 9.2 years. the mean (± standard error) serum concentrations of 25(oh) vitamin d3 were 36.6 ± 5.1 mg/dl, 50.1 ± 12.6 mg/dl and 19.8 ± 6.5 mg/dl in patients with mild, moderate and severe disease, respectively. there was a statistically significant inverse correlation between 25(oh) vitamin d3 concentration and edss score (p = 0.016, r= -0.273 by spearman rank correlation test), which was observed in women only (p = 0.021, r = -0.305). receiver operating characteristic curve analysis suggested that a serum 25(oh) vitamin d3 concentration cutoff of 16.5 mg/dl could differentiate patients with mild/moderate ms from severe disease with 74.6% accuracy. conclusion: our findings further support the association between vitamin d and disease severity in ms.