Relationship of Migraine and Tension-Type Headache With Hypothyroidism: A Literature Review.

BACKGROUND: Migraine, tension-type headache, and hypothyroidism constitute very common medical conditions. Headache is one of the most common symptoms of hypothyroidism, occurring in approximately one-third of the patients. To date, data about the relationship between migraine and tension-type headache and thyroid dysfunction, and in particular hypothyroidism have been contradictory, while the underlying pathophysiological basis explaining this association is still unclear.

OBJECTIVE: In this review, we investigated the association between primary headaches and hypothyroidism, with the aim of shedding light on its pathophysiological basis.

METHODS: We conducted a systematic search in the MEDLINE database using both subject headings and keywords for headache, migraine, tension-type headache, thyroid hormones, and hypothyroidism, and we also examined manually the reference lists of all articles that met the inclusion criteria. Included studies were related to headache and thyroid disease comorbidity, with emphasis on hypothyroidism (ideally demonstrated by hormonal measurements), and with the term headache including migraine, tension-type headache, and headache attributed to hypothyroidism (HAH) based on the International Classification of Headache Disorders IIIb. Quality of studies was assessed by the Newcastle-Ottawa scale.

RESULTS: Of a total of 640 identified articles, 9 studies were included. Overall, there was vast heterogeneity across the included studies concerning population, study design and outcomes. Two studies investigated the HAH, with emphasis on the clinical characteristics of headache (time of onset, localization, quality, intensity, and response to hormonal replacement treatment). Five studies investigated comorbidity between migraine and thyroid disorders, especially hypothyroidism, and in the majority of them a positive association was demonstrated. One study found that headache, and particularly migraine, may increase the risk of developing hypothyroidism. Finally, only 1 study on chronic tension-type headache found coexistence of migraine and hypoactivity of the hypothalamus-pituitary-thyroid axis. The strengths and limitations of these studies are analyzed and possible pathophysiological mechanisms are suggested.

CONCLUSIONS: The existing data are considered inadequate to answer with certainty the relationship between headaches and thyroid disorders. According to our analysis, it seems that suggestions for a possible bidirectional association between headaches and especially migraine and hypothyroidism could exist. It hence lays the foundation for further research into the aforementioned association and its pathogenesis via large prospective multicenter studies.