Calcitonin gene-related peptide in peripheral blood as a biomarker for migraine

There is no available biomarker for any of the primary headaches, including migraine. As demonstrated in jugular blood, during a migraine attack, trigeminal activation releases several neuropeptides, very especially calcitonin gene-related peptide (CGRP), which gives rise to the typical throbbing migraine pain. Here, we review the current evidence for measurement of peripheral CGRP levels as a potential biomarker for trigemino-vascular activation in migraine.Several studies, including a limited number of migraine patients, have shown increased peripheral CGRP levels during migraine attacks. The maximum increase in plasma CGRP levels was reached within 2 h of the onset of the attacks and can be reverted by triptans. In addition, CGRP levels measured in peripheral blood outside migraine attacks and in the absence of symptomatic medication have been shown to be increased in chronic migraine patients. Increased CGRP levels were able to predict the response to onabotulinumtoxinA treatment and were reduced 1 month after onabotulinumtypeA therapy.Although CGRP data must be confirmed and expanded in future studies and specificity of CGRP levels should be studied in entities able to resemble migraine, it seems that peripheral CGRP levels are a good biomarker of acute migraine and somewhat specific and sensitive interictally in chronic migraine.