As part of the endocrine system, thyroid disorders can affect fertility

Organs and glands in your endocrine system control many functions in your body through the release of hormones that carry messages through your blood to your organs, skin, muscles and other tissues. These signals tell your body what to do and when to do it. Because your thyroid is part of the body’s endocrine system, any thyroid disorders can affect your fertility.

Your thyroid is a butterfly-shaped gland that sits just below the Adam’s apple in your neck. As part of your endocrine system, the thyroid controls many of your body’s important functions by producing and secreting certain hormones. The thyroid’s main function is to control your metabolism and how your body uses energy. And, because it is one of the many organs and glands in your body’s endocrine system, it also plays a role in reproduction. Therefore, thyroid disorders can affect your fertility.

Thyroid disorders are common endocrine disease in young women. If you’re a woman, you’re up to 10 times more likely than men to have issues with your thyroid. Thyroid hormones that are either too low (hypothyroidism) or too high (hyperthyroidism) can contribute to infertility. Additionally, autoimmune thyroid diseases, such as Hashimoto’s thyroiditis or Graves’ disease, may have an impact on fertility.

Effects of an underactive thyroid on fertility

Underactive thyroid disorders can affect your fertility. When the thyroid gland produces low levels of its hormone, called hypothyroidism, this can interfere with the release of an egg during ovulation. If your problem is a sluggish thyroid gland you will need to go on thyroid hormone medication to get your thyroid hormone levels to the normal range to be fertile again. This change usually happens within three to six weeks of starting thyroid hormone therapy.

In addition, some of the underlying causes of hypothyroidism, such as certain autoimmune or pituitary disorders, may impair fertility. For example, Hashimoto’s thyroiditis, an autoimmune thyroid disorder, is the most common cause of hypothyroidism in the United States. It is caused by antibodies that attack the thyroid and destroy the gland. Women with Hashimoto’s are usually also infertile.

An overactive thyroid disorder can be more serious

Hyperthyroidism, when you have an overactive thyroid gland, is a more serious situation and harder to treat. An overactive thyroid can lead to elevated levels of the protein SHBG and the hormone prolactin, which can prevent the ovaries from releasing eggs. This can lead to infertility and other reproduction-related problems, including loss of pregnancy, menstrual disruptions, and preeclampsia.

In the short term, medication that tells your thyroid to produce less hormone helps. But if the disease progresses, you may need removal of the thyroid gland and possibly additional radioactive iodine therapy. If radioactive iodine is used, you must wait six to 12 months after treatment before trying to get pregnant because it isn’t safe for the fetus.

Diagnosing thyroid disorders during infertility treatment

The first step in diagnosing thyroid disorders that can affect your fertility is through a blood test that measures thyroid stimulating hormone (TSH). TSH levels are very important in helping to diagnose thyroid disorders as about 5% of women trying to conceive have abnormal TSH levels. During your initial fertility consultation, we routinely perform preliminary blood work to check many different hormones that can affect your fertility, including testing for abnormalities in TSH.