How Does Thyroid Health Affect Menstrual/Period Cycles?

How Does Thyroid Health Affect Menstrual/Period Cycles?

The menstrual cycle is influenced by a number of factors that may explain why women’s periods are sometimes regular, but on other occasions are irregular.


Menstruation depends on overall health and hormonal balance. Many health problems that women experience can affect their periods, and thyroid conditions are no exception.


Throughout this article, we are going to focus on thyroid health and its impact on the menstrual cycle.


Are menstrual problems common?

When menstrual problems occur, it may be easy to think that other women don't experience them.


However, according to the National Institutes of Health menstrual irregularities occur in about 14% to 25% of women of childbearing age[i].


These figures differ by the cause or nature of irregularity.


For example, if a woman has severe menstrual cramps, she might be included in the tally of women with endometriosis rather than among women with menstrual problems.


Moreover, many women do not report their menstrual problems to their healthcare providers.


What are the most common menstrual problems?

The normal menstrual cycle ranges from 21 to 35 days, but it is not uncommon for women to experience problems that disturb this cycle.


When the term menstrual problem comes to mind, we immediately think of late or missed periods, but multiple issues can affect your periods.


The most common menstrual irregularities include:


  • Absent menstrual periods (amenorrhea) – Occurs when a girl doesn’t get her period by the age of 16 or when an adult woman stops getting her periods for at least three months but she’s not pregnant
  • Infrequent menstrual periods (oligomenorrhea) – Periods occurring more than 35 days apart
  • Heavy menstrual periods (menorrhagia) – Excessive bleeding
  • Prolonged menstrual bleeding – Periods that last longer than eight days
  • Painful periods (dysmenorrheal) – Severe menstrual cramps


Besides the above-mentioned irregularities, women can also experience:


  • Frequent menstrual periods (polymenorrhea) – Having periods less than 21 days apart
  • Shortened menstrual bleeding – Periods lasting two days or shorter
  • Intermenstrual bleeding – Or spotting i.e., episodes of bleeding that occur between two periods
  • Irregular menstrual periods with cycle to cycle variation of 20 days or more


Thyroid problems common in women

The thyroid is a butterfly-shaped gland that produces thyroid hormones which play a role in a number of functions and processes in the body.


The thyroid can affect women's reproductive health and function too. A growing body of evidence confirms that thyroid problems are more common in women than in men[ii].


Both hypothyroidism and hyperthyroidism are more likely to affect ladies than men.


Let’s discuss how a thyroid disorder can affect menstruation.


Thyroid health and menstruation

Jacobson et al. confirmed that circulating thyroid hormone concentrations are associated with subtle differences in menstrual cycle function outcomes[iii].


Both hypothyroidism and hyperthyroidism can lead to menstrual disturbances.


Women with hyperthyroidism usually have decreased menstrual flow, but anovulatory cycles are also very common. Although heavier menstrual flows may occur, they are not quite common in hyperthyroidism. Since today, hyperthyroidism is spotted and diagnosed earlier than before, menstrual irregularities are less common than they used to be.


On the other hand, hypothyroidism is usually associated with increased menstrual bleeding, and disorders in homeostasis may contribute to the problem. Both hyper- and hypothyroidism are associated with reduced fertility, and the outcome of the pregnancy is more often abnormal than it is in euthyroid women[iv].


Ajmani et al. carried out a study on the role of thyroid dysfunction in patients with menstrual disorders.


They enrolled 100 women into their research and found that in subjects with menstrual disorders, 44% had thyroid conditions. Of these, 20% had subclinical hypothyroidism, 14% had overt hypothyroidism, while 8% had overt hyperthyroidism. Scientists concluded that thyroid dysfunction is a significant causative etiology of menstrual abnormalities.


As you can see, hypothyroidism is more commonly associated with menstrual problems than hyperthyroidism.


Menstrual disturbances may accompany and, in some cases, precede thyroid dysfunction. In the above-mentioned study, the most common menstrual problem was heavy periods[v].


Thyroid conditions can contribute to the failure to ovulate with resulting progesterone deficiency. Both hypo- and hyperthyroidism can affect pituitary hormones (LH, FSH, and prolactin).


Hypothyroidism can also deprive the ovarian follicles of the much-needed thyroid hormones that they require to develop properly[vi].


More about hypothyroidism and menstrual problems

A growing body of evidence confirms that this condition is strongly associated with insulin resistance which can eventually pave the way to metabolic disorders in hypothyroid women[vii].


Insulin resistance is a common occurrence in women with polycystic ovary syndrome (PCOS)[viii]. PCOS has a number of different symptoms and irregular menstrual periods and impaired cycle are also hallmark signs of this condition.


Women with PCOS are more likely to have autoimmune thyroiditis (Hashimoto’s thyroiditis) than their counterparts who don’t have this condition[ix]. This is yet another link between thyroid function and female reproductive health.


Hypothyroidism decreases levels of sex hormone binding globulin (SHBG)[x] which then, led to greater estrogen exposure and heavy periods.


On the flip side, hyperthyroidism can boost SHBG and contribute to light periods.


As discussed thoroughly, hypothyroidism and menstrual irregularities are connected. However, the underlying mechanisms require more studies that would elucidate them. Not only does adequate treatment help tackle symptoms of hypothyroidism, but it can also normalize the menstrual cycle. Inadequately managed and undiagnosed hypothyroidism is usually associated with:


  • Early menstruation – Hypothyroidism in young girls can trigger an early start of menstruation around the age of 10. For reference sake, the average age of the first period is around 12
  • Heavy menstrual periods – Earlier in the post we have already discussed that hypothyroidism can lead to heavy menstrual flow which can be quite uncomfortable
  • More frequent menstrual periods – Women with hypothyroidism may find that their periods occur more often than it is considered normal
  • Longer menstrual periods – Hypothyroidism may also contribute to longer menstrual periods where woman’s menstruation lasts six days or longer
  • Painful menstrual periods – It’s not uncommon for hypothyroid women to experience intense cramps, backaches, headaches, and stomachaches while on their periods


More info about hyperthyroidism and menstrual problems

Studies have connected hyperthyroidism with menstrual irregularities as well. These are the problems that may occur when hypothyroidism is undiagnosed or improperly managed:


  • Delayed puberty or late menstruation – Unlike hypothyroidism, which causes early onset of the first period hyperthyroidism can delay the start of puberty. Girls with hyperthyroidism may get their first period at 15 or older
  • Light menstrual periods – Hyperthyroid women tend to have periods that are lighter than normal
  • Shorter menstrual periods – While hypothyroidism can prolong your periods, hyperthyroidism can shorten them. Bear in mind that a short period isn’t automatically better
  • Sporadic menstrual periods – Hyperthyroid women may find that their periods don’t occur at a normal rate. They may have a period one month and a “pause” of month or two before the next period
  • Absent menstrual periods – Besides sporadic menstruations, women with hyperthyroidism may experience a complete absence of their periods for a certain period of time


When to see the doctor?

A major mistake that most women make is that they often wait for problems to go away on their own and avoid consulting their healthcare provider. When sudden changes in menstrual period and flow occur, it's a sign that something is wrong, and you should see the doctor in order to determine the cause of these irregularities and prevent potential complications in the future.


If these problems happen frequently, your doctor may want to evaluate thyroid hormone levels. In cases then thyroid conditions are to blame for menstrual irregularities proper management of those diseases could normalize your cycle as well.


You should also see your doctor if you have:


  • Intense or increased menstrual cramps
  • A thyroid condition and treatment, but menstrual irregularities still occur
  • Heavy menstrual bleeding lasting for more than 24 hours
  • Menstrual periods that last seven days or longer
  • Menstrual periods that come in a shorter timeframe than what is considered normal
  • Periods that stopped for about three months or longer and you are not pregnant


Maintaining a healthy menstrual cycle

The menstrual cycle isn't something we usually think about until problems occur.


Instead of being reactive i.e., waiting for problems to happen in order to do something about them, it's better to be proactive. Here are some tips that can help you maintain a healthy menstrual cycle:


  • See your doctor regularly, especially if you have some thyroid condition
  • Consume iron-rich food
  • Enrich diet with healthy fats
  • Exercise regularly
  • Practice yoga
  • Avoid exposure to products and substances which are known for their endocrine disrupting impact e.g., plastic, items with harsh ingredients, and others
  • Maintain weight in a healthy range
  • Eat a diet rich in vitamins and minerals rather than fast food
  • Manage stress
  • Get enough sleep



The menstrual cycle of every woman is influenced by a wide range of factors, including thyroid function.


A growing body of evidence confirms that thyroid hormones play a role in sexual and reproductive health of women, and that also includes the menstrual cycle. When the thyroid doesn't work properly, and the production of thyroid hormones is excessive or insufficient, consequences are felt in your menstrual cycle too.


For that reason, it's important to see your doctor when problems occur. In many cases, management of thyroid condition could also help tackle or eliminate problems with the menstrual cycle.




[i], How many women are affected by menstrual irregularities? National Institutes of Health. Retrieved from:


[ii]Bauer M, Glenn T, Pilhatsch M, et al. (2013). Gender differences in thyroid system function: relevance to bipolar disorder and its treatment. Bipolar Disorders; 16(1):58-71. Doi: 10.1111/bdi.12150. Retrieved from:


[iii] Jacobson MH, Howards PP, Darrow LA, et al. (2018). Thyroid hormones and menstrual cycle function in a longitudinal cohort of premenopausal women. Paediatric and Prenatal Epidemiology, 32(3):225-234. Doi: 10.1111/ppe.12462. Retrieved from:


[iv] Koutras DA. (1997). Disturbances of menstruation in thyroid disease. Annals of the New York Academy of Sciences; 816:280-284. Retrieved from:


[v] Ajmani, N. S., Sarbhai, V., Yadav, N., Paul, M., Ahmad, A., & Ajmani, A. K. (2016). Role of Thyroid Dysfunction in Patients with Menstrual Disorders in Tertiary Care Center of Walled City of Delhi. Journal of Obstetrics and Gynecology of India66(2), 115–119. doi:10.1007/s13224-014-0650-0. Retrieved from:


[vi] Poppe K, Velkeniers B, Glinoer D. (2007). Thyroid disease and female reproduction. Clinical Endocrinology, 66(3):309-321. Doi: 10.1111/j.1365-2265.2007.02752.x. Retrieved from:


[vii] Vyakaranam, S., Vanaparthy, S., Nori, S., Palarapu, S., & Bhongir, A. V. (2014). Study of Insulin Resistance in Subclinical Hypothyroidism. International journal of health sciences and research4(9), 147–153. Retrieved from:


[viii] Diamanti-Kandarakis, E., & Dunaif, A. (2012). Insulin resistance and the polycystic ovary syndrome revisited: an update on mechanisms and implications. Endocrine reviews33(6), 981–1030. doi:10.1210/er.2011-1034. Retrieved from:


[ix] Janssen OE, Mehlmauer N, Hahn S, et al. (2004). High prevalence of autoimmune thyroiditis in patients with polycystic ovary syndrome. European Journal of Endocrinology, 150(3):363-369. Retrieved from:


[x] Selva DM, Hammond GL. (2009). Thyroid hormones act indirectly to increase sex hormone-binding globulin production by the liver via hepatocyte nuclear factor-4α. Journal of Molecular Endocrinology, 43(1):19-27. Doi: 10.1677/JME-09-0025. Retrieved from:

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