The thyroid gland, a small butterfly-shaped gland located at the base of the front of your neck, plays an important role in your reproductive health, directly affecting your ovaries and indirectly interacting with sex-hormone binding globulin (a protein that binds sex hormones). Given this, thyroid dysfunction may result in menstrual irregularities—though menstrual problems tend to be more common in those with severe thyroid disease versus those with mild or moderate thyroid disease.If you are experiencing unusual symptoms during your menstrual cycle, it’s worth raising the possibility of a thyroid issue with your doctor.
Hypothyroidism
Hypothyroidism, or an underactive thyroid gland, is a disorder of insufficient thyroid hormone production. Common symptoms of hypothyroidism include:
- Feeling tired
- Weight gain
- Irregular menstrual cycles: cycles that are long or absent
- Heavy menstrual bleeding
- A higher sensitivity to cold
- Swelling and edema
- Dry skin and hair
- Thinning hair on the head
- Constipation
- Trouble becoming or staying pregnant
Types of disorder and menstrual disorders related to hypothyroidism
There are a number of menstrual irregularities associated with hypothyroidism, ranging from heavy, frequent menstrual bleeding to infrequent, or even absent, menstrual cycles.
Heavy Menstruation: According to the American College of Obstetrics and Gynecologists, heavy menstrual bleeding is defined by one or more of the following features:
- Bleeding that lasts more than seven days
- Bleeding that soaks through one or more tampons or pads every hour for several hours in a row
- Needing to wear more than one pad at a time to control menstrual flow
- Needing to change pads or tampons during the night
- Menstrual flow with blood clots that are as big as a quarter or larger
Keep in mind, while hypothyroidism is one potential cause of heavy menstrual bleeding, there are many other potential diagnoses, including fibroids, polycystic ovary syndrome (PCOS), medication side effects, uterine cancer, and infection, among others.
Absent or Infrequent Menstruation: On the opposite end of the spectrum, absent periods (amenorrhea) or infrequent periods (oligomenorrhea) may occur with hypothyroidism. Infrequent menses are more common. Amenorrhea or oligomenorrhea can occur from the increase in thyroid releasing hormone (TRH) in women with hypothyroidism. The high TRH levels trigger the release of prolactin by the pituitary gland (a pea-sized organ located at the base of the brain). Prolactin interferes with the production of estrogen from the ovaries, causing infrequent or absent periods, as well as other potential symptoms like infertility, an abnormal milky discharge from the breasts (galactorrhea), and symptoms of menopause, such as hot flashes and vaginal dryness.
Early menstruation: The average age of menarche (the first period) is around 12 in the U.S. Hypothyroidism in young girls can trigger an unusually early start of menstruation, before the age of 10, for example. This early puberty is known as “precocious puberty.”
More frequent menstrual periods: Hypothyroidism is known to cause periods to come more frequently, a condition known as polymenorrhea. You may find that your period comes every 21 days, for example, instead of the average 28-day cycle.
The relationship between hypothyroidism and infertility
The body-wide hormone changes that hypothyroidism (underactive thyroid) can cause may lead to irregular menstrual cycles and other problems with menstruation that can affect fertility. Hypothyroidism disorders that affect fertility include:
- Prevent ovulation
- Cysts in the ovaries
- Increased prolactin production
- Increased risk of miscarriage
The upside here is that treatment of hypothyroidism with thyroid hormone replacement medication (levothyroxine) may correct infertility and decrease the risk of pregnancy loss. That said, some women with hypothyroidism continue to experience abnormal menstrual cycles, despite thyroid medication.
Reference
https://www.verywellhealth.com/menstrual-problems-and-thyroid-disease-3231765
https://helloclue.com/articles/cycle-a-z/hypothyroidism-and-the-menstrual-cycle
https://www.healthcentral.com/article/preparing-for-pregnancy-when-youre-hypothyroid
https://www.everydayhealth.com/thyroid-conditions/thyroid-issues-and-fertility.aspx
