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.