Serum iron may not be linked with migraine.

Sir,

‘We are thankful to the authors for their interest in this manuscript.[1] We agree with the fact that exclusion of subjects with iron deficiency would have improved the quality of our study. To support it, they have cited a study that shows that iron deficiency might be related to menstrual migraine.[2] We did not consider exclusion of iron-deficient subjects owing to a number of facts: First, this was not the aim of the study; second, considering a high prevalence of iron deficiency in India, this was not practical; lastly, iron deficiency has been reported in a number of Restless Legs Syndrome patients.

As far as the relationship between iron and migraine is considered, this could be an over-simplistic explanation for this complex issue. The cited article had enrolled subjects with migraine whereas inclusion criterion in the present study was RLS.[2] Hence, both the studies cannot be compared directly. In addition, that study had found a relationship between menstrual migraine and iron deficiency but not between migraine and iron deficiency.[2] Thus, this finding cannot be generalized to all migraineurs. Moreover, a study that enrolled the RLS patients, like our study, did not find any effect of serum iron on the migraine.[3] To make the issue more complex, a number of studies have reported increased iron depiction in deep brain nuclei among migraineurs.[45] On the other hand, iron has been found to be decreased in the central nervous system of RLS patients.[67]

In conclusion, more work is required to understand this complex issue.