New Type of Migraine May Be Due to Low Iron

November 04, 2016

Many women who have migraine toward the end of menstruation may be best treated with iron supplements, a new study suggests.

In a paper published online in the journal Headache, Anne Calhoun, MD, and Nicole Gill, DO, Carolina Headache Institute Durham, North Carolina, describe a new type of headache dubbed "end-menstrual migraine."

They explain that this is "a not-uncommon yet not previously typified headache disorder, which we are simply calling 'end-menstrual migraine'…due to its proximate occurrence with the terminal days of menstrual bleeding each month."

The report describes 30 women with this condition, most of whom were found to have low levels of ferritin, suggesting that iron supplementation may be a suitable treatment.

They believe that end-menstrual migraine is not hormonally mediated but rather causally related to menstrual blood loss, resulting in a brief relative anemia with consequent migraine. "Further study is needed to substantiate this association, search for confounders and evaluate response to iron therapy," they conclude.

"This is migraine which occurs at the end of the menstrual period — maybe on the last few days of bleeding or after the bleeding has stopped," Dr Calhoun, who runs a menstrual migraine clinic, explained to Medscape Medical News. "It is not the same thing as menstrual migraine, which generally occurs on the day or two before menstruation or on the first day or two of bleeding and is known to be hormonally mediated. If migraine occurs 5 days or more after the onset of bleeding this is not classic menstrual migraine."

She explained that menstrual migraine is very common, is normally caused by the withdrawal of estrogen, and can be treated with hormone therapy.

"But this new phenomenon of 'end menstrual migraine' is different," she said. "Some women have both menstrual and end-menstrual migraine. I kept coming across women with menstrual migraine. After treatment with hormones this would improve, but they would still get a headache but later on. Other women only get a headache at the end of the menstrual period, and these headaches were not responding to hormone treatment."

She estimates that up to 20% of her patients have this type of migraine.

Dr Calhoun started to look for other ways to treat these women and started wondering about iron levels. "We know children can get headaches due to anemia, and these women are experiencing migraine after acute blood loss each month. It seemed worth investigating. Also, restless legs syndrome is common in women with migraine and has also been linked to low ferritin levels," she said.

While there has not yet been a formal study of iron supplementation in these women, Calhoun is convinced such treatment works. "I see these patients day in day out, and I can tell you that giving them iron does make them better. Virtually all of them respond. It may take a few months and if they are very low in ferritin they may need an iron infusion. But, yes, a formal study would be the next step."

For the current study, the authors assessed the relationship between patients with migraine occurring at the end of menstruation and their blood ferritin levels.

They examined their menstrual migraine clinic's database to find patients with migraine, regular menses, and the locally used diagnostic code of EMM, signifying the patient's assertion that she had migraine at the end of menses as well as calendar data confirming that association. Because ferritin levels are routinely drawn in this particular clinic in such women, serum ferritin levels were available for all these patients.

Results showed that among the most recently seen 119 women in the clinic, 85 had both regular menses and a diagnosis of migraine and were thus appropriate for evaluation. In this selected population, 30 women (35.3%) were confirmed to have end menstrual migraine.

Of these, 28 (93.3%) had ferritin levels that fell below the generally accepted lower desirable limit of 50 ng/mL (mean, 21.9 ng/mL), and half had levels below 18 ng/mL, the established minimum levels for women.

While menstrual migraine itself is now recognized, Dr Calhoun says it does not receive the medical attention it deserves. She estimates that about half of all women who experience migraine have headaches around the time of menstruation.

"It is an enormous issue, but these women may have problems accessing the correct treatment as it falls between specialities," she commented. "Most neurologists don't think about hormones, and most gynecologists don't deal with neurological conditions — we really need a new speciality field of nonsurgical hormone-related issues. And now we believe that not all menstrual-related migraine is the same, so there is even more to think about."

Not a New Concept

Commenting on the study for Medscape Medical News, Anne MacGregor, MD, Centre for Neuroscience & Trauma, Barts and the London School of Medicine and Dentistry, United Kingdom, and one of the leaders in the field of menstrual migraine, said: "Migraine linked with heavy periods has been thought about and written about for years — it just hasn't been given a name."

Professor MacGregor added that this type of migraine may not necessarily be caused by low iron levels.

"We know that one of the factors associated with menstrual migraine is prostaglandin release, which is increased in women with heavy, painful periods. This is a completely independent mechanism from estrogen withdrawal," she said. "Previous studies have shown that these women benefit from approaches that treat the menstrual problem, such as prostaglandin inhibitors (such as mefenamic acid or naproxen), the Mirena intrauterine device, or other contraceptive methods, such as the combined pill."

The study received no outside funding. The authors have disclosed no relevant financial relationships.

Headache. Published online October 5, 2016. Abstract

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