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May 16, 2023 7 min read

Have you noticed something different about your menstrual cycle since you started taking levothyroxine? You might be wondering if it's just a coincidence or if there's actually a connection between the two. Well, you've come to the right place! Below, we'll take a look at the connection between levothyroxine and changes in the menstrual cycle to determine if this medication is indeed responsible for the changes you're experiencing.

What role does the thyroid stimulating hormone play in our body?

The human body has many different types of glands, and one of them is the thyroid gland. It plays a crucial role in regulating many important functions in your body, including metabolism, growth, and development.

Your thyroid gland produces and secretes thyroid hormones, mainly thyroxine (T4) and triiodothyronine (T3), which regulate the body's metabolism. These hormones control the rate at which your body uses energy and affect many body processes, such as heart rate, digestion, body temperature, and protein production.

The thyroid gland also plays a vital role in the growth and development of the body, particularly the brain, during infancy and childhood. It helps regulate the release of other hormones, such as growth hormones and reproductive hormones and plays a critical role in maintaining a healthy immune system.

The thyroid gland and its hormones are essential for the proper functioning of many organs and systems in the body. Disruptions in thyroid function can lead to a range of thyroid dysfunction. The main thyroid diseases are hyperthyroidism and hypothyroidism.

Hyperthyroidism, or overactive thyroid, is a condition that occurs when you have too much thyroid hormone in your body. On the other hand, hypothyroidism, also known as underactive thyroid, happens when you have too little thyroid hormone.

Hypothyroidism is the more common of the two. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), around 4.6% of people in the US over the age of 12 years old have a mild form of hypothyroidism. One of the main causes is Hashimoto's thyroiditis, an autoimmune disease in which the immune system mistakenly attacks the thyroid gland. Numerous other things can affect thyroid function, such as thyroidectomy (removal of the thyroid gland) and goiter (enlarged thyroid).

A woman having period cramps.

How do thyroid hormones influence menstrual cycle?

Menstrual cycles are a captivating interplay of hormones in women's bodies, and thyroid hormones are part of this delicate dance. That's why one of the consequences of thyroid disorders like hypothyroidism is changes in the menstrual cycle. Women with this thyroid disorder may experience longer, heavier periods, shorter cycles, or even missed periods. These changes are due to the hormonal imbalances caused by not having enough thyroid hormones.

The thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3) play a vital role in the regulation of the menstrual cycle. They interact with other hormones, such as estrogen and progesterone, to ensure that the menstrual cycle functions correctly. When the levels of thyroid hormones are low, this delicate balance is disrupted, leading to menstrual irregularities.

Moreover, hypothyroidism can also cause an increase in testosterone, luteinizing stimulating hormone (LH), and follicle-stimulating hormone (FSH) levels, all of which can lead to skipped, irregular, or heavier periods.

What is levothyroxine?

Levothyroxine is a synthetic version of the naturally occurring thyroid hormone thyroxine (T4). As the go-to medication for thyroid hormone replacement therapy, it plays a vital role in effectively treating the thyroid disease hypothyroidism. The primary function of levothyroxine is to replenish the deficient thyroid hormone levels, thus restoring balance within the body and ensuring the smooth functioning of various metabolic processes.

Once administered, levothyroxine is absorbed into the bloodstream and then converted into triiodothyronine (T3), the active form of thyroid hormone that the body needs to function optimally.

Levothyroxine is typically taken orally as a daily dose, with the dosage adjusted based on your individual needs. Blood tests are used to monitor thyroid hormone levels and ensure that they remain within the normal range. It's crucial for you to adhere to your prescribed dosage and maintain regular follow-up appointments with your to ensure optimal treatment outcomes.

What causes changes in the menstrual cycle while on levothyroxine?

As levothyroxine helps to restore normal thyroid hormone levels in patients with hypothyroidism, it can also lead to changes in menstrual periods. These changes are generally positive, as they reflect the normalization of the hormonal balance within the body. But sometimes, people have not-so-great changes in their periods. Instead of being more regular, periods can be heavier or lighter, happen more often or not at all, and some people might even have non-stop spotting.

It's essential to point out that the negative changes in menstruation experienced by some women taking levothyroxine could be due to various reasons.

When a woman with hypothyroidism starts taking levothyroxine, her thyroid hormone levels begin to normalize. This can have a cascading effect on other hormones involved in the menstrual cycle, potentially leading to changes in menstruation. Additionally, it's worth noting that the process of finding the correct dosage of levothyroxine can take some time, and fluctuations in hormone levels during this period can further contribute to menstrual irregularities.

Another factor to consider is our body's unique response to synthetic hormones. Some individuals might just have a less-than-ideal reaction to levothyroxine, causing disruptions in their periods. For example, if a woman is started on levothyroxine and her thyroid hormone levels increase rapidly, it will increase the levels of sex hormone binding globulin (SHBG). This can lead to menstrual irregularities, such as lighter or skipped periods.

It's also possible that you don't respond well to levothyroxine because your body can't convert T4 to T3 hormone effectively. Remember that T4 is an inactive thyroid hormone that needs conversion into T3 for your body to benefit from it. So, if your body has difficulty converting T4 to T3, levothyroxine, which only contains the T4 hormone, may not be as helpful as it should be.

In rare cases, some women may develop hyperthyroidism due to taking too high a dose of levothyroxine. This can result in lighter, less frequent periods or even the cessation of menstruation altogether. On the other hand, if a woman is not taking enough levothyroxine to treat her hypothyroidism fully, she may continue to experience menstrual irregularities, such as heavy or prolonged periods.

A woman having period pain while jogging.

How to address negative menstrual changes due to levothyroxine

If you're experiencing negative changes in your menstrual cycle after starting levothyroxine, it's essential to talk to your doctor about these concerns. They can help determine whether the changes are related to your medication or if there may be another underlying cause. Here are some steps that can be taken to address these issues:

1. Adjustment of levothyroxine dosage

Your doctor might tweak your levothyroxine dosage to balance your hormone levels and reduce menstrual changes. If your current dose is too low, they may increase it; if it's too high, they'll decrease it. However, it's important not to change your dosage without consulting your doctor first. Be sure to follow their guidance and have routine blood tests to keep an eye on your TSH levels.

2. Additional medication

In some cases, your doctor may prescribe additional medication to help regulate your menstrual cycles, such as birth control pills or progesterone supplements.

3. Lifestyle modifications

Making certain lifestyle changes can also help improve menstrual regularity and alleviate symptoms. These changes can include maintaining a healthy weight, eating a balanced diet, exercising regularly, and managing stress.

4. Try other thyroid hormone replacement medications.

If changes in the menstrual cycle occur because you're not responding well to levothyroxine, thus, you have untreated hypothyroidism, it might be a good idea to switch to another thyroid medication. One promising alternative is natural desiccated thyroid (NDT). NDT comes from the thyroid glands of pigs and contains both T4 and T3 hormones. Many people consider NDT to be a more "holistic" approach to thyroid hormone replacement therapy since it closely resembles our body's natural hormone production.

Various brands of NDT are available, such as Armour Thyroid and NP Thyroid. NDT supplements, like VitaliThy, are also an option to explore. VitalIThy, a natural desiccated thyroid you can buy online, is free from common allergens like lactose, gluten, fish, shellfish, and eggs. It also doesn't use any artificial coloring or flavoring. Therefore, it's great for those who have certain food sensitivities.

When should you consider switching from levothyroxine to NDT?

If you're experiencing negative changes in your menstrual cycle due to levothyroxine, you might be wondering when it's the right time to consider switching to natural desiccated thyroid (NDT). Here are some factors to keep in mind:

1. Persistent menstrual irregularities

If you've tried adjusting your levothyroxine dosage with your doctor's guidance, but your menstrual cycle continues to be irregular, it might be worth discussing the option of NDT.

2. Inadequate response to levothyroxine

If your hypothyroid symptoms, including menstrual changes, aren't improving despite being on an appropriate levothyroxine dosage, you may want to talk to your doctor about trying NDT.

3. Difficulty converting T4 to T3

If blood tests show that your body is having trouble converting T4 to the active T3 hormone, NDT could be a more effective treatment option, as it contains both T4 and T3 hormones.

4. Preference for a "holistic" approach

If you're interested in a more holistic approach to thyroid hormone replacement therapy, NDT might be a better fit for you, as it closely resembles the body's natural hormone production.

Remember, it's essential to consult with your doctor before making any changes to your thyroid medication. They can help you determine if NDT is a suitable option for you and guide you through the process of transitioning from levothyroxine to NDT, if necessary.

If you're intrigued by the idea of trying NDT, it's a great idea to start with a supplement like VitaliThy. This NDT supplement offers a comprehensive thyroid hormone profile, as it contains not only the T4 and T3 hormones but also T2, T1, and calcitonin.

These additional components provide more well-rounded hormonal support, and some users may find it more effective in addressing their hypothyroid symptoms, including menstrual irregularities. T2 and T1 hormones, although less studied, are believed to play a role in metabolism and overall thyroid function. Calcitonin, on the other hand, is involved in calcium regulation, and it could potentially contribute to better bone health.

Wojciech Majda
Wojciech Majda

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