25‑hydroxyvitamin d concentrations in patients with optic neuritis as a clinically isolated syndrome and healthy controls

objectives: the onset of multiple sclerosis in the majority of the cases occurs as a clinically isolated syndrome (cis). we sought to assess serum levels of 25-hydroxyvitamin d (25-ohd) in cis patients and healthy controls. methods: in this cross-sectional study 40 patients (36 women and 4 men) with cis manifesting as a single isolated optic neuritis and 40 age- and sex-matched healthy controls (35 women and 5 men) were enrolled between late october 2010 and early march 2011. general vitamin d deficiency was defined as serum 25-ohd levels of lower than 20 ng/ml and was classified as mild (15 < 25-ohd <20 ng/ml), moderate (8 < 25-ohd <15 ng/ml), and severe (25- ohd <8 ng/ml). results: we found no difference in the median interquartile range [iqr] between cis patients and controls (17.95 [10.40- 29.13] vs. 17.00 [12.25-31.00]; p =0.57). however, when stratified by the levels of deficiency, among cis patients a significantly higher proportion had severe vitamin d deficiency in comparison to healthy controls (20% vs. 2.5%; p =0.034). nevertheless, the frequency of general (62.5% vs. 60%, p =0.82), mild (25% vs. 30%, p =0.80), and moderate (17.5% vs. 27.5%, p =0.42) vitamin d deficiency were not different between the two groups. conclusions: our findings do not indicate any significant difference of serum 25-ohd between cis patients and healthy controls. however, in our series severe vitamin d deficiency was more frequent among cis patients.