The study published in the Neurology journal of the American Academy of Neurology found that as estrogen levels fluctuate, levels of the protein calcitonin gene-related peptide (CGRP) play a key role in starting the migraine process. 

Women with episodic migraines were divided into three groups for the study: those with regular menstrual cycles, those using oral contraceptives, and those who had experienced menopause. There were 30 persons in each group, for a total of 180.

To measure CGRP levels, researchers collected blood and tear fluid. The samples were obtained from women with regular menstrual cycles both during menstruation, when estrogen levels are lowest and around ovulation when levels are highest. Both the hormone-free and hormone-intake times were used to collect samples from people using oral contraceptives. Postmenopausal participants samples were collected once at a random time.

The study discovered that women with migraine and a regular menstrual cycle had greater levels of CGRP during menstruation than women without migraine. CGRP levels were comparable in postmenopausal women and those using oral contraceptives. Blood levels in migraine sufferers were 5.95 picograms per millilitre (pg/ml), compared to 4.61 pg/ml in non-migraine sufferers.

In contrast, CGRP levels were comparable between the migraine and non-migraine groups in female participants taking oral contraceptives and in the postmenopausal stage.

Reliable measurement in the blood is difficult due to its extremely short half-life. Although this approach is non-invasive, it is still exploratory. Experts said the study also implies that detecting CGRP levels through tear fluid is feasible and merits further investigation.

They further emphasized the need for a larger trial to validate the current findings and were optimistic that the results would help better understand the migraine process.

(Source: https://theprint.in/health/low-estrogen-levels-paired-with-higher-cgrp-levels-may-jump-start-migraine-study/1394931/)