Thyroid and menopause

What is the thyroid gland?

The thyroid gland is butterfly-shaped and is found in the front of your neck. It produces the hormones thyroxine (T4) and tri-iodothyronine (T3). Thyroxine is converted by the tissues and organs that need it into the active hormone tri-iodothyronine. In healthy people, the production of these hormones is regulated by the secretion of thyroid-stimulating hormone (TSH) from the pituitary gland in the brain. Thyroid hormones regulate the metabolism of the body's cells.

How do we diagnose thyroid problems?

A blood test for thyroid function is performed to check the diagnosis of a thyroid problem. If you have thyroid swelling, scans may also be needed.

Hypothyroidism is usually managed by a GP, whereas hyperthyroidism will be treated, at least initially, by a thyroid specialist (endocrinologist). Borderline results may need to be repeated and monitored, sometimes with specialist advice from an endocrinologist. Thyroid swelling may not need a specialist. But if your doctor is concerned, they will refer you to a thyroid specialist.

Underactive thyroid  (hypothyroidism)

The two most common causes of an underactive thyroid (hypothyroidism) in the UK are;

• Autoimmune thyroid disease (Hashimoto's disease; where your body's immune cells mistakenly damage the thyroid gland and stop it from working)
• Side effects of treatment for an overactive thyroid or thyroid cancer (thyroid surgery or radioactive iodine treatment)

When there is too little thyroid hormone, the body's metabolism slows down. Symptoms include fatigue, lethargy, weight gain, dry skin and hair, low mood, impaired concentration and memory and constipation. Thyroxine (or levothyroxine) is the thyroid hormone replacement recommended in the UK.

It is important to be aware that thyroid symptoms can be non-specific, meaning there can be many other causes for such symptoms. Therefore if you have severe symptoms and your thyroid blood tests are normal or borderline, there are likely to be other factors contributing to your symptoms.

Nowadays, we do more thyroid testing, and it is not uncommon to be told your thyroid tests are borderline. If you are unwell for other reasons, this can impact your thyroid tests as a one-off. Your doctor will usually arrange a repeat test. If the repeat test is normal, it is unlikely that your thyroid is the cause of your symptoms. If your thyroid tests remain borderline or worsen, you may have subclinical hypothyroidism. This can sometimes, but not always, cause symptoms and can progress to an underactive thyroid. Your doctor may start you on treatment to see if it helps your symptoms.

Overactive thyroid (hyperthyroidism)

Thyroid overactivity (hyperthyroidism) is less common, affecting around 1.5% of women of this age. There are two leading causes of hyperthyroidism in the UK:

• Autoimmune thyroid disease (Graves' disease) accompanied by TSH-receptor antibodies in the blood.
• One or more benign (non-cancerous) thyroid nodules which can secrete excess thyroid hormone

When there is too much thyroid hormone, the body's metabolism speeds up. Symptoms include fatigue, sweating, heat intolerance, weight loss, difficulty sleeping, shaking, heart palpitations with a fast or irregular heartbeat and anxiety. Patients with Graves' disease may develop eye problems such as grittiness and soreness, protrusion of the eyeballs and rarely, problems with vision. Hyperthyroidism may be managed with antithyroid drugs, radioiodine treatment or thyroid surgery.

Thyroid and menopause

Thyroid problems in women

The risk of developing an underactive thyroid gland increases with age. It is about 10 times more common in women than men. So it is common for midlife women going through menopause to also have an underactive thyroid. It's thought that 12–20% of women over the age of 60 years may have an underactive thyroid.

Both thyroid and menopause-related symptoms are common, non-specific and overlapping. Such symptoms can also have other causes, like stress. So it is important to talk to your doctor about the potential causes of your symptoms. It is not unusual for thyroid symptoms to be put down to menopause and vice versa. And as these problems are common in midlife women, symptoms may be a combination of factors that should all be addressed.

The additive effect of hypothyroidism and menopause can impact the overall burden of symptoms facing midlife women. Therefore optimising the management of both hormone conditions is crucial.

Declining oestrogen levels may affect the thyroxine dose required

Your thyroxine dose requirements may change during your menopause transition. This can relate to changing oestrogen levels and other factors, such as changes in your weight. It is usual for you to have a yearly blood test to check your thyroid levels, which will show if you need a change in your treatment dose.

Hormone Replacement Therapy (HRT)

HRT is currently the most effective treatment for menopause symptoms. Therefore, it is recommended as a first-line treatment for such symptoms if you need treatment support.

Women with no pre-existing thyroid disorder and normal thyroid function usually adapt well to the effects of the HRT, and their thyroid function remains normal.

Thyroid replacement is not a contraindication to HRT. Women with pre-existing hypothyroidism may require an increase in their thyroxine dose after starting oral combined HRT because oral oestrogen changes the amount of thyroxine bound to proteins in your blood and can result in less free thyroid hormone that is available to do its job. Therefore it is helpful for thyroid function tests to be re-checked after starting tablet-combined HRT.

When oestrogen is given through the skin by gel, spray or patch, the dose of thyroxine should not be affected. Progesterone in HRT is not expected to significantly impact thyroid replacement doses.

Compounded (unlicensed) formulations of HRT

These are not recommended for symptoms of menopause because it is generally unclear how safe and effective they are. Furthermore, their production is not subject to the same regulations as Formulary drugs and may interact with other prescribed medicines. Some reports have shown increased vaginal bleeding on such unregulated treatments and even womb cancer.

Phytoestrogens

Soy foods are a traditional component of Asian diets. However, their alleged health benefits have boosted their popularity in recent years. Most attention has focused on phytoestrogens, leading to the development of phytoestrogen supplements and the fortification of foods with soybean constituents.

Despite the possible benefits, there have been some concerns that soy may adversely affect thyroid function and interfere with the absorption of thyroid hormone medication. Evidence suggests that soy foods may inhibit the absorption of thyroxine and increase the dose of thyroid hormone required by hypothyroid patients.

However, there is little evidence that soy foods or phytoestrogen supplements affect thyroid function in people with normal thyroid function. Soy foods may increase the risk of hypothyroidism in people with borderline thyroid function and low iodine intake. Therefore, it is essential for people who regularly consume soy food to ensure their consumption of iodine is adequate.

Calcium supplements

Women with hypothyroidism who take calcium carbonate supplements should ensure they do not take their calcium supplement within four hours of the thyroxine dose. Calcium carbonate may decrease the absorption of thyroxine by nearly a third when these medications are taken at the same time.

Iodine supplements

Too much iodine can interfere with thyroid function and make existing thyroid conditions worse. So you should not take supplements that contain high-doses of iodine. Kelp (brown seaweed) should also not be taken as a source of iodine.

This is because its iodine content is highly variable and may lead to excessive iodine intake which can cause problems.  Standard over-the-counter supplements that contain up to 100% of your daily recommended intake of iodine are; however, ok to take.

Healthy unprocessed food sources (eggs, milk, cheese, fish etc) that are naturally high in iodine are fine to consume in normal dietary quantities.

Osteoporosis and thyroid

Oestrogen levels drop around the time of menopause, resulting in increased bone loss. This loss of bone density leads to less bone strength and increased risk of breaking bones. The thyroid gland plays a crucial role in maintaining healthy bones. So it is vital to have your thyroid optimally treated to keep your bones strong.

In postmenopausal women, an overactive thyroid (hyperthyroidism) is a risk factor for hip fracture.

Overtreated hypothyroidism is also associated with an increase in fracture risk.

Whether borderline (subclinical) hyperthyroidism is associated with an increased fracture risk remains less certain as there is insufficient data to draw definite conclusions in all patient groups.

Alternative/complementary treatments for menopause symptoms

Many women who have milder menopause symptoms choose to avoid taking HRT. For some women, HRT is not tolerated or may be unsafe for other medical reasons. These women may seek alternative or complementary treatments, such as herbal remedies.

Before starting alternative, complementary or 'natural' medicines, you should get advice from your doctor or pharmacist, especially about how it may affect your thyroid condition  We also recommend checking the patient leaflet that comes with your medication for any possible interactions.

Frequently Asked Questions (FAQs)

Can women with hypothyroidism start perimenopause/menopause earlier?

Treated hypothyroidism is not explicitly associated with early menopause. However, Premature Ovarian Insufficiency (POI) is associated with autoimmune thyroid disease. Thyroid problems can occur in 14–27% of women with POI, so these women should be tested for thyroid peroxidase antibodies and screened for thyroid-stimulating hormone levels at presentation.

Can people with hyperthyroidism start perimenopause/menopause earlier?

Hyperthyroidism does not specifically cause an earlier menopause. Uncontrolled hyperthyroidism can cause stress across your hormone system. For this reason, it can affect, and even stop, menstrual periods in fertile women and increase perimenopausal symptoms in women who are already nearing, or in, the menopause transition. Once the overactive thyroid is treated, these effects may subside. They may also continue if your body was already heading towards perimenopause before the thyroid problem began.

If I am prescribed testosterone, could this interfere with my thyroid medication?

If you are prescribed testosterone and your blood levels are normal, this should not impact your thyroid medication. Very high doses of testosterone (used as anabolic steroids, not replacement doses) can affect thyroid levels.

How can I tell if my symptoms relate to my thyroid condition or menopause?

That is not easy. Your doctor should ensure that your thyroid levels are optimised. If your symptoms continue and there are no other apparent causes menopause is the likely culprit. Lifestyle can help a lot with menopause symptoms, but if you continue to struggle, then talk to your doctor about treatment options.

Can having a thyroid condition make menopause symptoms worse?

Yes, it can because thyroid hormones control your metabolism. So, if your thyroid function is not stable and your metabolism is either too high, too low, or changing rapidly, that can impact in different ways on your menopause symptoms. However, as long as your thyroid condition is treated optimally, and is stable, there should be minimal impact on your menopause symptoms.

If women without a thyroid condition are presenting with menopause-like symptoms, should their thyroid function also be checked? 

If you have developed typical menopause symptoms after the age of 45 years, then a thyroid test is not usually needed. 

If you have severe symptoms that are not consistent with menopause alone, or if you have any ‘red flag’ features identified by your doctor, such as unexplained weight gain, weight loss or palpitations, among other symptoms, then your doctor will check your thyroid levels.

Is it safe to take menopause supplements and other preparations if I have an existing thyroid condition?

It is important to take thyroid hormone medication on an empty stomach. You can take such supplements, but you should not take ones containing calcium within about four hours of your thyroid medication. You should also always wait at least 30 minutes after you take your tablet before consuming food, milk, tea or coffee.

Conclusions

Thyroid disorders may cause similar symptoms to menopause. Tablet oestrogen in HRT and phytoestrogen supplements do not affect normal thyroid function; however, they may impact doses of thyroid medication in women treated for hypothyroidism. HRT given through the skin by gel, patch or spray do not impact thyroid replacement doses however.

Women considering alternative, complementary or 'natural' medicines for menopausal symptoms should get advice from their doctor or pharmacist.

Thanks to Prof Annice Mukherjee for helping us to update this article. Prof Mukherjee is a consultant endocrinologist with a special interest in menopause and is a published author on this subject.

A previous version of this article by Dr Jackie Gilbert was published in The Menopause Exchange newsletter.

May 2023

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