Medically reviewed by
Dr. Minako Abe, M.D., Board-certified emergency medicine physician researching the relationship between lifestyle and disease onset in relation to the immune system and cancer, Japan
While we often associate the thyroid with energy regulation and metabolism, its influence extends far beyond. The thyroid gland and the menstrual cycle are two critical elements that play a vital role in a woman’s well-being.
According to the American Thyroid Association, approximately one in every eight women will develop a thyroid condition at some point in their life. If you are living with a thyroid condition such as hypothyroidism or hyperthyroidism, you may already have noticed that some of your symptoms include problems with your period.
The interplay between the thyroid and the menstrual cycle is indeed both fascinating and crucial, as imbalances in thyroid hormones can significantly impact menstrual regularity, fertility, and overall hormonal harmony. This intricate relationship has long been a subject of interest among researchers.
In this article, we will address some ways in which the thyroid gland affects the menstrual cycle as well as possible ways to mitigate the undesired effects of thyroid dysfunction on the menstrual cycle.
What exactly is the interplay between the thyroid and the menstrual cycle?
How does the thyroid affect the menstrual cycle?
The menstrual cycle, a recurring process of the female reproductive system, is governed by a complex interplay of hormones. The cycle has four main distinct phases namely menstruation (the menstrual phase), the follicular phase, ovulation, and the luteal phase.
Thyroid hormones, particularly thyroxine (T4) and triiodothyronine (T3), play a role in regulating the menstrual cycle by influencing the hypothalamic-pituitary-gonadal (HPG) axis. Thyroid hormones influence the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus, which in turn influences the secretion of gonadotropins – luteinizing hormone (LH) and follicle-stimulating hormone (FSH) – from the pituitary gland. These hormones control the function of the gonads (ovaries). From the ovaries, the sex steroid hormones estrogen and progesterone are produced. These sex hormones orchestrate the changes in the uterine lining and the release of an egg from the ovaries.
Owing the role of the thyroid gland, through processes mediated by the thyroid hormones, in regulating major functions of the female reproductive system, imbalances in these thyroid hormones can lead to female reproductive issues. One of such conditions that could arise is polycystic ovary syndrome (PCOS), a condition that often involves irregular periods, fertility challenges, and hormonal imbalances.
This goes without saying that thyroid dysfunction, such as hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid), can in fact disrupt the normal functioning of the menstrual cycle. In cases of autoimmune thyroid disorders such as Hashimoto’s thyroiditis (autoimmune hypothyroidism) and Graves’ disease (autoimmune hyperthyroidism) which are driven by the immune system attacking the thyroid, the menstrual cycle may also be impacted by the immune system’s effect on hormone production and regulation.
Generally, hypothyroidism and hyperthyroidism can each manifest in distinct ways within the context of the menstrual cycle:
Hypothyroidism and Menstrual Effects:
- Anovulation: Low thyroid hormone levels can disrupt the hormone cascade required for ovulation (release of a mature egg from the ovary), leading to skipped or irregular periods and fertility issues. Anovulation can also result in abornally heavy and prolonged menstrual bleeding (menorrhagia).
- Amenorrhea: Hypothyroidism may result in the absence of periods altogether, which also indicates potential fertility issues.
Hyperthyroidism and Menstrual Effects:
- Early menopause: Hyperthyroidism, especially autoimmune hyperthyroidism (Graves’ disease), can lead to the premature onset of menopause (typically when menopause begins before the age of 40)
- Lighter periods: Increased thyroid activity may lead to reduced menstrual flow or lighter, infrequent periods (oligomenorrhea)
Conditions such as amenorrhea, oligomenorrhea, and anovulation can present in women living with either hypothyroidism or hyperthyroidism.
Other concerns worthy of note when it comes to the effect of the thyroid on the menstrual cycle are stress and pregnancy.
Stress, both physical and emotional, can impact thyroid function and menstrual health. The body’s stress response can alter the hypothalamic-pituitary-thyroid (HPT) axis, leading to changes in thyroid hormone production. In response to stress, cortisol is released into the bloodstream from the adrenal glands. Excessive cortisol in the bloodstream can affect hormonal production from the hypothalamus, resulting in the disruption of the normal production of the thyroid hormone, as well as the suppression of reproductive hormones. This, in turn, can affect the menstrual cycle and fertility. Chronic stress can contribute to a cascade of hormonal imbalances that ultimately disrupt the regularity of periods.
Pregnancy is a period of immense hormonal changes, and the thyroid is no exception. The thyroid undergoes some physiological changes to accommodate the increased demand for thyroid hormones for the mother and fetus. Thyroid disorders during pregnancy can lead to complications like preterm birth, preeclampsia, and developmental issues for the baby. Following childbirth, women can experience shifts in thyroid function that may affect their menstrual cycle. Postpartum thyroiditis, characterized by a typically transient thyroid dysfunction, can lead to irregular periods, making the return to normal menstrual cycles a gradual process.
Now that we have briefly addressed how the thyroid affects the menstrual cycle, it is time to explore whether the reverse is also true.
So, does the menstrual cycle also have an effect on thyroid health?
While the effect of the menstrual cycle on thyroid health is not as well-studied and well-documented as the effect of thyroid function (or dysfunction) on the menstrual cycle, some observations affirm the possibility of the menstrual cycle’s impact on thyroid function.
Some women may experience changes in thyroid function tests (such as TSH levels falling slightly outside the reference range) during their menstrual cycle owing to fluctuations in estrogen levels. In some cases, TSH levels may be lower than normal during the follicular and luteal phases of the menstrual cycle. TSH levels may also increase in response to high circulating levels of estradiol (the most potent form estrogen) mid-cycle.
Due to the fluctuations in TSH levels across the various phases of the menstrual cycle, it is recommended that, in order to ensure accurate test results, thyroid function tests are consistently performed in the same phase of the menstrual cycle. The precise timing of the phases of the menstrual cycle for the purpose of thyroid function tests may, however, be a challenge.
How can thyroid-related menstrual issues be managed?
Addressing thyroid-related menstrual irregularities involves a comprehensive approach. Consulting with a healthcare provider, often an endocrinologist or gynecologist, is crucial for accurate diagnosis and treatment. Regular monitoring of thyroid hormone levels, in conjunction with medical advice, can help restore normalcy to menstrual cycles. Thyroid function tests, such as TSH and free T4 tests, can help determine the nature and extent of thyroid dysfunction.
Treatment for thyroid-related menstrual issues essentially depends on the underlying thyroid disorder. Treatment options may include medication to regulate thyroid function, lifestyle modifications, and, in some cases, surgery.
Hypothyroidism is typically managed with thyroid hormone replacement therapy (levothyroxine), which can restore thyroid hormone balance and as a result, help regulate the menstrual cycle. According to a study published in the Iranian South Medical Journal in 2017, levothyroxine is even capable of alleviating menstrual issues in euthyroid women (women with a normal-functioning thyroid).
Hyperthyroidism, on the other hand, may require antithyroid medications, radioactive iodine (RAI) therapy, or in some cases, surgery. One major caveat with the use of RAI therapy for hyperthyroidism is that it is not safe for pregnancy. According to the American Thyroid Association, women should avoid pregnancy for about a year or at least 6 months following RAI treatment in order to mitigate the risks of miscarriage, premature birth, and birth defects. RAI has also been associated with irregular menstrual cycles in some women.
Maintaining a healthy lifestyle is also key to supporting thyroid function and menstrual health. Always remember that adequate nutrition, stress management, regular exercise, and sufficient sleep all contribute to hormonal balance and overall well-being.
Key Takeaways
- One in every eight women will experience some form of thyroid condition during their lifetime.
- If you experience problems with your periods or menstrual cycle in general, your underlying thyroid condition may be at the root of it.
- Once your thyroid hormones are out of balance, whether too high or too low, your menstrual periods may be affected. They might be heavy, light or irregular.
- The menstrual cycle, as well as other processes of the female reproductive system are likely to be negatively affected due due to hormonal imbalances stemming from stress, the immune system, or other factors that can have an impact on thyroid function.
- Postpartum thyroiditis can also cause menstrual problems in some women after childbirth.
- Not only can thyroid dysfunction affect the menstrual cycle, but there is also evidence to suggest that the menstrual cycle can also affect thyroid function.
- In case you experience some unusual menstrual symptoms, you should consult with your healthcare provider. You may need some thyroid function tests to evaluate whether your thyroid is at the root of the problem.
- Some common menstrual disorders include:
- Anovulation – No release of an egg (ovum) during the menstrual cycle.
- Amenorrhea – Absence of menstrual periods.
- Oligomenorrhea – Infrequent or light periods.
- Menorrhagia – Heavy and prolonged periods.
- Whether you have an underlying thyroid condition or none that you are aware of, it is best to seek medical attention as soon as possible. ·
- Regular check-ups and open communication with healthcare providers are essential for individuals experiencing menstrual irregularities or thyroid-related concerns.
- Thyroid disorders can often be managed with medication, lifestyle changes, and proper medical guidance.may n
