How hypothyroidism can affect your menstrual cycle

How hypothyroidism can affect your menstrual cycle


7 minute read

Medical conditions, like hypothyroidism, can cause irregular periods. If your menstrual cycle changes, it is worth discussing the situation with your primary care provider.

Defining hypothyroidism

What does the thyroid regulate?

To understand conditions impacting the thyroid, we must first explore what the thyroid is. The thyroid is a small hormone-producing organ located in the front of the neck shaped like a butterfly. The thyroid regulates many bodily functions including metabolism, growth, and body temperature. Thyroid hormones can impact several systems when it is not functioning normally, including your menstrual cycle.

What is hypothyroidism?

Hypothyroidism is when the thyroid is underactive and doesn’t produce enough thyroid hormones to function at normal levels. Symptoms often appear slowly over time.

There are two forms of hypothyroidism: subclinical hypothyroidism and hypothyroidism. With subclinical hypothyroidism, typical symptoms may not be present, or if present, may be mild. This condition is recognized by high levels of thyroid-stimulating hormone (TSH) and oftentimes normal levels of thyroxine (T4). This form is often only diagnosed when routine labs are drawn, or if symptoms suddenly become noticeable. 

With hypothyroidism, there is noticeable under-functioning of the thyroid. Blood tests will show low levels of thyroxine (T4), a hormone impacting growth and metabolism, and high TSH. 

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), about 4.6% of the US population over 12-years-old has a mild form of hypothyroidism. Women are more likely to be affected, especially those with a history of thyroid issues. Many thyroid problems are hereditary and it’s useful to know your family’s medical history. You are more likely to develop hypothyroidism if you’ve:

  • Experienced previous thyroid problems, such as goiter 

  • Had thyroid surgery

  • Needed radiation treatment for your thyroid, neck, or chest 

When are thyroid conditions likely to develop?

For women, thyroid issues can often develop right after pregnancy. The cause isn’t clear but, according to the Mayo Clinic, women who produce antibodies that attack their thyroid after pregnancy likely have an underlying autoimmune disease that appears when their immune function changes. You are also in a higher risk category if you:

  • Are female

  • Are over 60-years-old

  • Have thyroid diseases in your family history

  • Have an autoimmune disorder

  • Have had thyroid surgery or received radiation treatment

Causes of thyroid issues

Hypothyroidism can be caused by:

  • Autoimmune diseases, such as Hashimoto’s disease

  • Iodine deficiency

  • Physical or medical damage

  • Pregnancy

  • Certain medications

In the United States, the most common cause for hypothyroidism is Hashimoto’s disease. This is an autoimmune disease in which the immune system mistakenly attacks the thyroid. The damage done when the immune system attacks the thyroid leads to hypothyroidism.  

Iodine is used in the production of thyroid hormone, so if there isn’t enough in your body, it can result in hypothyroidism.

Previous thyroid problems, including physical or medical damage, can make developing hypothyroidism more likely. Surgery or radiotherapy affecting the thyroid gland can lead to hypothyroidism, as can conditions affecting your immune system such as type 1 diabetes, anemia.

The changes to your immune system during pregnancy potentially lead to hypothyroidism as well. 

Hypothyroidism symptoms in women

With hypothyroidism, many bodily functions are slowed, including metabolism. As a product of your slowing metabolism, due to hypothyroidism, changes may develop slowly with feelings of fatigue or sluggishness as the first noticeable expression. Other signs of this condition include:

  • Sensitivity to cold

  • Constipation

  • Muscle weakness

  • Unexplained weight gain

  • Joint or muscle pain

  • Depression

  • Exhaustion

  • Pale, dry skin

  • Dry, thinning hair

  • Slow heart rate

  • Excessive menstrual bleeding

If you have any of these symptoms, contact your primary care provider for assessment and treatment.

Thyroid and periods

When there is a hormonal imbalance, like with hypothyroidism, it can deregulate the menstrual cycle. This can lead to light, heavy, or irregular periods. It can also cause amenorrhea, meaning your period may stop for 3 or more months. The imbalance of hormones can also affect other areas of your body. There may be an interaction between thyroid hormones and estrogen, a hormone produced in the ovaries, resulting in early menopause. If menopause occurs before the age of 45, it is considered early.

Hypothyroidism is likely to have an impact on your period because it causes an abnormality of hormone function. Signs of period irregularity include:

  • Discoloration of the blood 

  • Blood clots

  • Cramps that require heat or medication

  • Length or severity of the period.

Please note, hypothyroidism is not the only cause of irregular periods. Stress, certain birth control methods, and perimenopause can all impact the menstrual cycle. If you are experiencing irregularity in your menstrual cycle, consult with your primary care provider.

Living with hypothyroidism

Treatment for hypothyroidism

Hypothyroidism is usually treated with a synthetic version of thyroid hormone. The medication is a pill that is usually taken once, daily. Depending on the cause of diagnosed hypothyroidism, you may need to take this medication for the rest of your life given that thyroid hormone is an essential bodily function.

Does thyroid medication affect the menstrual cycle?

With any hormonal changes, the menstrual cycle can be impacted. With hypothyroidism, changes can appear in a variety of ways including changes in the frequency and/or severity of your period. The medication, though not necessarily the cause of the issue, might bring other hormonal issues to the surface in the form of irregular periods.

Irregular periods are listed as a side effect of thyroid medications. Let your primary care provider know of any changes to your cycle.

Does thyroid medication cause weight gain?

Weight gain can be a side effect of hypothyroidism, but with a proper dose, the medication should bring your metabolism back to normal. That being said, weight may be gained once again if treatment is changed for any reason. Other side effects of medication can include:

  • Sweating 

  • Chest pain 

  • Headaches 

  • Diarrhea  

  • Vomiting

You should note that taking medication for hypothyroidism will not make you lose weight. The goal of treatment is to return your hormone levels to your metabolic baseline. Additionally, several factors can contribute to weight gain while on thyroid medication. Certain foods, such as walnuts and soybean flour, can interact poorly with your medication. To avoid negative interactions, make sure to avoid consuming these foods for several hours before and after taking your medication. Be sure to discuss any side effects of your medication with your primary care provider.

Holistic treatments

While holistic treatments are not scientifically-proven, they may improve your overall well-being while dealing with hypothyroidism. Holistic treatments for hypothyroidism include:

  • Increasing iodine intake

  • Increasing vitamin D intake

  • Increasing selenium intake

  • Having a self-care routine

  • Increasing activity levels

These suggestions are intended to help you manage the condition, not cure it. Taking care of your stress levels and maintaining both a healthy diet and exercise routine help your lifestyle. Consider discussing holistic treatments with your primary care provider.

Managing hypothyroidism

There is a lot of information out there on managing hypothyroidism. Pay attention to how you are feeling and note any changes in your daily life. Consider factors such as your energy levels and any changes to your menstrual cycle. 

If you have concerns about how hypothyroidism is impacting your life, including your menstrual cycle, please discuss your options with your primary care provider. 

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