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Cycle A-Z

Hypothyroidism and the menstrual cycle

by Nicole Telfer, Science Content Producer
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Top things to know

  • The thyroid gland is involved in regulating many of the body’s functions, like metabolism, growth, body temperature
  • People with hypothyroidism do not produce enough thyroid hormones
  • Some common symptoms of hypothyroidism include: tiredness, weight gain, dry skin, and irregular menstrual cycles
  • Hypothyroidism is usually treated with medication that is a synthetic version of a thyroid hormone.

What is hypothyroidism?

The thyroid gland is a small hormone-producing organ located in the front of the neck. The thyroid gland regulates many of the body’s functions, including metabolism, growth, heart rate, and body temperature.

For someone with hypothyroidism, the thyroid gland does not produce enough thyroid hormones. This causes a general slowing down of many of the body’s functions, and can lead to changes in the menstrual cycle (1). Hypothyroidism affects up to 2 in 100 people, with women being more affected than men (2-4).

Symptoms: What you might notice if you have hypothyroidism

For a while, someone may just sense that something is “off” in their body. With time, symptoms become more noticeable. 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
  • Goiter (abnormal growth/enlargement of the thyroid) (1,5-8)

Causes: Why hypothyroidism happens

The thyroid gland produces two main hormones: thyroxine (T4) and triiodothyronine (T3). When someone has hypothyroidism, their thyroid gland doesn’t produce enough of these hormones. This can happen for a few different reasons:

Iodine deficiency

In some places where malnutrition or iodine-deficient soil exists, people are not able to get enough iodine (a natural mineral) in their diets. Without enough iodine in the diet, people can develop an iodine deficiency. This can cause hypothyroidism and a goiter (a swollen and enlarged thyroid gland) to develop (3,9).

Autoimmune disease

In places where people have access to enough iodine in their diet, hypothyroidism is most often caused by an autoimmune disease called Hashimoto's disease (10). This disease causes a person’s immune system to attack their thyroid gland, preventing it from working properly (10). It’s not yet clear what causes this to happen.

Physical or medical damage to the thyroid

Hypothyroidism can also develop when the thyroid is physically damaged. This can happen when someone is receiving treatment for hyperthyroidism or having surgery or radiation around the area of the thyroid (7). Medication, such as lithium, can also cause hypothyroidism as a side effect (11).

Pregnancy

Pregnancy can cause a disorder called postpartum thyroiditis. Postpartum thyroiditis usually begins between two and six months after childbirth, and generally lasts up to one year (12). Symptoms of postpartum thyroiditis are usually mild and can include hyperthyroidism (an overactive thyroid) and/or hypothyroidism symptoms. Postpartum thyroiditis affects about 7 in 100 pregnancies, and should be managed with the help of a healthcare provider (12). About 1 in 5 people with postpartum thyroiditis develop hypothyroidism that is lifelong (4,13).

How hypothyroidism is diagnosed

Hypothyroidism can be diagnosed in two forms: subclinical hypothyroidism and hypothyroidism.

People with subclinical hypothyroidism do not usually have any of the typical symptoms. On laboratory blood tests their thyroid hormones (T4) are shown to be within normal ranges (20). Subclinical hypothyroidism is diagnosed through laboratory tests, which indicate that the thyroid stimulating hormone (TSH—the hormone that signals from the brain to the thyroid) is above the normal range (20). Subclinical hypothyroidism is more common than typical hypothyroidism (14,21). Some people with subclinical hypothyroidism can progress to develop hypothyroidism.

In comparison, people diagnosed with hypothyroidism have clear underfunctioning of their thyroid gland and often have typical symptoms. The blood laboratory results of someone with hypothyroidism have low levels of thyroid hormones (T4) and high levels of thyroid stimulating hormone (TSH) (22).

A healthcare provider will probably ask questions about symptoms and medical, family, and menstrual history. In particular, they will want to hear about possible miscarriages or trouble getting pregnant. They will likely perform a physical exam. If the healthcare provider thinks a thyroid disorder might be present, they will likely run some blood tests to measure levels of thyroid hormones. In some cases, an ultrasound of the thyroid gland will be performed.

Why get checked for hypothyroidism?

Thyroid disorders are manageable once they’ve been diagnosed, but it can be difficult to spot their symptoms. Across the United States, it is estimated that almost 1 in 20 people have a form of hypothyroidism (14). Hypothyroidism is more common among women than men, and the prevalence increases with age (14). Left untreated, symptoms of hypothyroidism (like weight gain and tiredness for example) can impact a person’s quality of life. They can also lead to complications such as lowered heart function, recurrent miscarriages, infertility, and birth defects during pregnancy (7,8,15,16). Untreated hypothyroidism can cause decreased mental processing, a goiter (an enlarged thyroid), and in rare cases, a loss of consciousness or coma (17,18).

Pregnancy can change medication needs for people with thyroid disorders. It is important to talk to your healthcare provider if you have a thyroid disorder and are, or are planning to become, pregnant (4,19).

Hypothyroidism treatment

Thyroid disorders are most often treated or managed with medications to balance the levels of thyroid hormones in the body. In most cases, treatment for thyroid disorders is lifelong.

Medications: Hypothyroidism is treated with a hormone replacement medication. A synthetic version of the hormone thyroxine (T4) is usually prescribed (10).

Lifestyle/alternative treatments: Increasing iodine intake through iodized salt is an easily accessible and affordable way to prevent iodine deficiency (23).

It is still not clear if there is a connection between certain foods, herbs, or other vitamins and their impact on thyroid function (10,24). More research is needed here.

If you think you could have a thyroid condition, tracking your cycles and symptoms with Clue can provide your healthcare provider with information that may help with diagnosis and in forming a treatment plan. Early treatment can reduce the risk of serious complications such as heart problems, depression, recurrent miscarriages, infertility, and birth defects during pregnancy (15,7,8,16).

What to track

If you suspect you might have hyperthyroidism, it can be helpful to keep a record of your symptoms. Here is what we recommend you track in Clue.

Essential to track

  • Bleeding patterns

Helpful to to track

  • Weight
  • Blood volume
  • Emotions
  • Energy
  • Mental
  • Stool
  • Hair
  • Skin

Download Clue to track your menstrual cycle and symptoms

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