How Thyroid Function Affects Menstruation

March 25, 2021

The thyroid gland is a very important gland in terms of reproductive health. It directly affects the ovaries and interacts with the sex-hormone-binding globulin (a protein). Hence, thyroid dysfunction can lead to problems with menstruation, although it’s more common in people with severe thyroid disease as compared to those with mild or moderate thyroid disease. So, as per the top gynaecologists in India, if you notice any irregularities with your menstrual cycle, please don’t ignore them. Contact your doctor at the earliest.

Issues Related to Hypothyroidism

An underperforming thyroid gland is called hypothyroidism. It can lead to a number of menstrual problems such as heavy, frequent menstrual bleeding to infrequent, or even absent, menstrual cycles.

Heavy Menstruation

Heavy menstrual bleeding is characterised by:

  • Bleeding that persists for more than seven days
  • You’d need one or more tampons or pads every hour for several hours in a row to stop the bleeding
  • The compulsion to wear more than one pad at a time (to control menstrual flow)
  • Menstrual flow that has blood clots

Note: You should be aware that heavy menstrual bleeding can be caused by other conditions as well: fibroids, polycystic ovary syndrome (PCOS), medication side effects, uterine cancer, and infection, among others. Thus, it’s better to confirm your diagnosis with your gynaecologist.

Absent or Infrequent Menstruation

Strangely, the same condition can also cause absent periods (amenorrhea) or infrequent periods (oligomenorrhea). Although infrequent menstruation is more common, both these conditions can occur due to an increase in the thyroid-releasing hormone (TRH) in women with hypothyroidism. A high level of TRH triggers the secretion of prolactin by the pituitary gland. Prolactin affects the production of estrogen, thus causing absent or infrequent menstruation. It can also cause other conditions like infertility, galactorrhea (an abnormal milky discharge from the breasts), and symptoms of menopause, such as hot flashes and vaginal dryness.

Decreased Fertility

Because of a decrease in thyroid production, ovulation can get considerably affected, which can make it difficult to get pregnant. Moreover, women who are already pregnant are at a greater risk of miscarriage in the first trimester. The good news is this can be avoided with medication. Thyroid hormone replacement medication (levothyroxine) can correct infertility and decrease the risk of miscarriages. That said, some women would still continue to experience abnormal menstrual cycles, despite medications.

Issues Related to Hyperthyroidism

Even excess secretion of the thyroid hormone can cause problems with menstruation. The most common ones are absent or infrequent menses. This is because the increased thyroid hormone indirectly leads to increased secretion of the sex hormone-binding globulin (SHBG), which prevents ovulation. Hyperthyroidism leads to the same problems as hypothyroidism - missed periods, decreased fertility and increased risk of miscarriages.

In conclusion, the severity of thyroid disease increases the chances of menstrual dysfunction. But that also doesn’t mean that having normal menstruation cycles rules out any thyroid problem. Irregular menstruation is surely an indicator of some underlying condition.

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