Thyroid hormones, similar to estrogen, progesterone and testosterone hormones, act on cells to direct the synthesis and release of various proteins. These hormone-mediated proteins are responsible for structure and function of many tissues, including genital tissues. Female genital tissues, similar to other tissues in the body, depend upon thyroid hormone for regulation of cell metabolism. For example, thyroid hormone acts on clitoral and vaginal smooth muscle cells to improve the responsiveness of the smooth muscle. The tone of the smooth muscle in the clitoris and vagina determines the state of sexual arousal. Clitoral and vaginal smooth muscle cells relax during sexual arousal to allow for blood to engorge the tissues. The health of the smooth muscles cells is, in part, determined by the action of the thyroid hormone.
Hyperthyroidism is a condition caused by having too much thyroid hormone act on the body’s tissues. Women with hyperthyroidism usually experience: i) feeling hotter than those around them, ii) losing weight even though they may be eating more, iii) fatigue at the end of the day, but often complain of trouble sleeping, iv) trembling of the hands and a hard or irregular heartbeat or palpitations and v) irritability and a tendency to become easily upset. Usually the symptoms of hyperthyroidism are very gradual so women with the condition don’t even realize they are experiencing problems.
In a study of 350 women with various menopausal symptoms, including sexual dysfunction, all women had blood tests for thyroid function. The study showed that 18 (5.1%) had hyperthyroidism. Improvement in menopausal symptoms occurred after treatment of the thyroid dysfunction. Another study addressed the sexual dysfunctions in patients with hyperthyroidism and their resolution after normalization of thyroid hormone levels. A total of 34 had hyperthyroidism. In hyperthyroid patients various sexual dysfunctions were found. After thyroid hormone normalization in hyperthyroid subjects, sexual dysfunctions improved.
In summary, some patients with thyroid hormone disorders experience some sexual dysfunctions which can be reversed by normalizing thyroid hormone levels.