Decreased urinary level of melatonin as a marker of disease severity in patients with multiple sclerosis.

Melatonin has both pro-inflammatory and anti-inflammatory properties depending on the stage of inflammation. Despite its therapeutic effect in alleviation of some symptoms of multiple sclerosis; the precise role of melatonin in MS pathogenesis remains a topic of debate. The aim of this study was to measure the urine level of one of melatonin products which is an index of serum melatonin level, in MS patients in the acute phase of relapse and control patients. We also analyzed different clinical and cognitive indices in order to find any correlation with melatonin level. Twenty eight patients who were diagnosed as relapsing-remitting MS, according to the revised McDonald criteria, along with 10 age- and sex-matched control subjects were recruited in our study. Here we showed that urine 6-sulphatoxymelatonin levels (aMT6s; the major metabolite of melatonin) were significantly lower in MS patients compared to control group. Interestingly, urine aMT6s levels significantly correlated with MS Functional Composite score, but not Expanded Disability Severity Score. Based on above findings, there might be new hope in developing a quantitative and objective measure to assess the MS severity especially in neurodegenerative diseases. However, our results should be analyzed cautiously. We didn't evaluate simultaneous level of 25-OH Vitamin D. It has been recently reported that there is a negative correlation between melatonin and vitamin D levels. Further studies are needed to confirm this hypothesis.