Thyroid conditions or abnormalities affect disproportionately more women than men and can lead to a detrimental impact on health, writes medical researcher and female health advocate, Dr. Emily Handley.

What is the thyroid?

The thyroid is a butterfly-shaped gland that sits at the base of the neck and produces thyroid hormone. The critical role of the thyroid in the body is determined by levels of thyroid hormone, traveling through the bloodstream to control metabolism via heart rate and rate of calories burned. Metabolism works to process food eaten into energy, and the thyroid controls this process through two specific hormones; T4 (known as thyroxine) and T3 (known as triiodothyronine). When functioning correctly, your thyroid regulates the exact amount of energy cells in the body need to use by maintaining hormone levels; as hormones are used, the thyroid continually creates T3 and T4 as replacements. The pituitary gland – sitting below the brain – monitors the amount of T3 and T4 in the bloodstream, and when hormone levels are out of whack, adjusts this by creating its own hormone: thyroid stimulating hormone (TSH). This hormone acts exactly how you would expect – after being sent to the thyroid, it dictates the gland’s next actions to maintain body homeostasis.

What are thyroid disorders?

Thyroid dysfunction occurs when the gland releases too much or too little hormone. When making too much thyroid hormone, the body uses up energy too quickly; alternatively, too little thyroid hormone can result in fatigue and weight gain. Thyroid disorders are the second most common endocrine disorder – disorders of our body’s messenger system – in women of reproductive age, and have been associated with low iodine levels. There are three main thyroid disorders: hyperthyroidism (an overactive thyroid and too much hormone), hypothyroidism (an underactive thyroid and too little hormone) and thyroid cancers.

Learning about different hormones and functions of our body’s endocrine system can be overwhelming, but knowing the specific hormone imbalances you might be experiencing can be key to correct diagnoses and treatments.

Hyperthyroidism

Hyperthyroidism can be thought of the body speeding up – all of our body’s functions accelerating, including the production of thyroid hormones. With more thyroid hormone, our cells are cued to use more energy than is sustainable, and metabolism begins to rocket upwards. The most common cause of hyperthyroidism is Graves’ disease, an autoimmune condition where the immune system attacks the thyroid and becomes overactive. An overactive thyroid can induce irregular heart rhythms (arrhythmias), delirium/mental confusion and even heart failure. Plummer’s disease is another known cause of hyperthyroidism – where small thyroid nodules form and produce thyroid hormone, without responding to feedback from TSH.

The symptoms of hyperthyroidism can go undetected for years due to their slow onset – but at a certain point, become very hard to ignore. These include:

• Rapid weight loss combined with greater hunger/eating habits
• Irregular/pounding heartbeat
• Anxiety
• Sleeping disturbances
• Trembling hands or fingers
• Bulging eyes or irritation
• Weaker/fewer menstrual periods
• Muscle weakness
• Increased sweating and hot flashes

If left untreated, these symptoms can combine and become a critical situation; where heart failure/arrhythmia and overheating require emergency medical care. Hyperthyroidism also increases the risk of osteoporosis – where bones are weakened and break more easily. This occurs most often in women who have gone through menopause, and needs to be tested for in light of any of the above symptoms.

Hypothyroidism

On the other hand, hypothyroidism is the slowing of the body – where not enough of the T4 hormone is produced, due to either the pituitary gland, the hypothalamus in the brain or the thyroid not working properly. There are three levels of hypothyroidism that affect symptoms and treatment: overt, subclinical or secondary. Overt hypothyroidism shows clear symptoms and is diagnosed easily –where the body has high levels of TSH, but lower levels of T4. Subclinical hypothyroidism is harder to detect; symptoms can be vague or overlap with other conditions. This is the most common form of hypothyroidism, and occurs TSH is higher, but T4 levels are normal T4. Finally, there is secondary hypothyroidism; this is caused by another disorder, such as dysfunction of the pituitary gland or brain regions. This condition features low TSH and low T4, and is the least common of the three classifications. The characteristic symptoms of any form of hypothyroidism are:

• Muscle weakness or pain
• Unexplained weight gain
• Thinning/dry hair
• Slow heart rate
• Feeling sad, tired and/or depressed
• A raspy voice
• Face swelling and pale, dry skin
• Heavier menstrual periods
• Feeling cold more often
• Constipation

Hypothyroidism is also linked with high cholesterol (LDL, the ‘bad’ type) which can then increase the risk of heart disease.

Thyroid Cancers

When cancer cells form from the tissue of the thyroid gland, symptoms can be almost non-existent. Most people with thyroid cancer often have a small nodule of the thyroid, or swelling of the neck. This may feel like a lump that causes problems with swallowing, and may even change a person’s voice. While most thyroid nodules are not cancerous, it is important if you feel any kind of lump in your throat to ask you doctor to check for cancer.

How do thyroid disorders affect women?

Thyroid disorders can wreak havoc at any stage of a woman’s life – from puberty to post-menopause, thyroid imbalances can interact with the reproductive system. Knowing the signs of thyroid dysfunction and the impacts it has on women can be a life-saver when discussing treatments and understanding symptoms.

During puberty and menstrual years an overactive thyroid causes abnormally early menstruation, while the opposite is true for an underactive thyroid – pushing back the onset of puberty. Additionally, high or low levels of thyroid hormones can result in abnormally light or heavy periods, or cause them to become irregular or absent. An out-of-whack thyroid can also impact ovulation and reproduction – the release of an egg for fertilisation. Having an undiagnosed thyroid disorder can stop ovulation all together, while an underactive thyroid can increase the risk of ovarian cysts. A severely underactive thyroid can even result in abnormal milk production, while also halting ovulation. Importantly, thyroid disorders during pregnancy can have harmful impacts on the foetus and lead to thyroid issues postpartum. Abnormally low levels of thyroid hormone can result in stillbirth; preterm birth; miscarriage; and post-partum haemorrhage. Higher levels of thyroid hormone put women at a greater risk of severe morning sickness, and can impact the blood pressure and heart rate of the mother. Treating thyroid disorders during pregnancy is particularly sensitive to individual needs and requires an extensive history of symptoms to make informed treatment decisions.

The symptoms of an overactive thyroid are often mistaken for menopause; and indeed, thyroid disorders can cause early menopause. Treating hyperthyroidism can sometimes prevent early onset menopause and ease related symptoms – such as thyroid-related insomnia, lack of menstruation, mood swings and hot flashes. Along with female-specific symptoms and outcomes, women are more at risk for thyroid disorders. Having significant overlap between reproductive phases and disorders, identifying the clinical symptoms of thyroid dysfunction can be difficult and delay diagnosis and treatment. But why is it that women are so impacted by this small, butterfly-shaped gland?

Why are women affected by thyroid disorders?

Scientists are still working to fully understand why women are so prone to developing thyroid problems; but it’s thought that autoimmunity (where the immune system attacks other systems in the body) is a likely culprit. Autoimmune diseases are more often seen in women than men, and again, we don’t fully understand why this is the case. We do know though that there is a complex interplay between the lifestyle, environmental and genetic factors that meet and create the perfect storm. Another likely suspect is the ever-prominent hormone estrogen. In conditions where estrogen levels are relatively higher than the other female hormone progesterone, this hormone imbalance has been linked to thyroid dysfunction. The links between the thyroid and female sex hormones are clear, but yet to be fully untangled.

What raises the risk of thyroid dysfunction in women?

While anyone can develop thyroid disorders, there are specific risk factors for women that increase the likelihood of a disease being diagnosed.

A family history of thyroid disease or autoimmune disease is one of the greatest risk factors for developing a disorder. Having knowledge of your family history is an important tool in knowing how to advocate for your own health and understand what any changes in your health might indicate. Any kind of radiation or toxin exposure is another life event that can increase the risk of thyroid disease; this includes radiation therapy of the head or neck, ingesting toxins, or workplace exposures.

By maintaining a healthy diet and being aware of any workplace dangers, you can reduce the potential toxic load that you may be inadvertently exposed to. Other lifestyle factors linked to thyroid disease include smoking; injury to the thyroid gland; mental stress; medications with high iodine; or residing in an area that has an iodine deficiency.

Stress in particular can be a sign of imbalances in the stress-response system, beginning in the brain and including the adrenal glands that produce your hormones. Chronically elevated cortisol levels due to stress can inhibit production of thyroid hormone, and the conversion of inactive thyroid hormone to the active form. Iodine in particular is a critical micronutrient and a part of the thyroid hormones T4 and T3 that keep the gland ticking along. Large changes in iodine levels create a cascade that can lead to a lifelong thyroid disorder. You can test for iodine levels with your doctor if you suspect your intake is unbalanced.

For women in particular, the likelihood of developing thyroid disorder skyrockets immediately after pregnancy or menopause. Particularly during menopause, it can be difficult to tease apart symptoms of either condition, making understanding the different symptoms even more pertinent. Having a history of miscarriage, infertility or preterm births is another indicator of future thyroid dysfunction. Thyroid problems are also more likely to affect older women during their post-menopausal years.

Testing for thyroid disorders.

So, what next? You’ve identified risk factors and you know you’re experiencing symptoms or suspect something is not quite right – how do you find out if this is all linked to your thyroid? Most doctors rely on blood tests to identify thyroid dysfunction – looking for differing levels of thyroid hormones. These tests can identify:

• TSH: elevated levels may mean hypothyroidism and vice versa for hyperthyroidism. If abnormal, further tests may be done for T4 and T3 to better understand the problem.
• T4: tests for both hypo- and hyperthyroidism, and monitors the treatment of these disorders. High T4 may indicate hyperthyroidism, with low T4 indicating hypothyroidism.
• FT4/Ffree T4 or F3/free T3: a highly accurate measurement that only measures unbound (‘free’) T4 or T3 in the body.
• T3: diagnoses hyperthyroidism, and can be used to determine the severity of hyperthyroidism. This test is most useful for managing hyperthyroidism.

While these tests alone don’t always provide a clear diagnosis, they can be invaluable for prompting additional testing that provide a clearer diagnosis. It’s important to understand your normal ranges of thyroid hormones; one person’s normal range may differ from another, so it’s vital to ensure you have a baseline from which you can monitor any changes. Sometimes, what the eye can see is the most foolproof way of identifying issues. Imaging tests that scan the thyroid and allow your doctor to see changes in the size and shape, as well as the presence or growth of nodules. A radioactive iodine uptake test is delivered via liquid or capsules that hold small amounts of radioactive iodine. This collects in your thyroid and measures how efficiently your thyroid is using iodine to make hormone. High levels mean your thyroid makes too much thyroid hormone, and vice versa for low levels. There are three types of thyroid nodules that might also be detected by this test:

• Hot nodules take up more radioactive iodine than the thyroid and show up brightly on the scan. They make more hormone than normal, and less than 1% are found to be cancerous.
• Warm nodules take up the same amount of radioiodine as the thyroid, and make a normal amount of hormone. Approximately 5-8% of these are found to be cancerous.
• Cold nodules take up significantly less radioiodine and are dark areas when scanned. Up to 15% are cancerous, and these are the more common form of nodule identified.

The thyroid can also be visualised through an ultrasound. Ultrasounds provide information as to what type of nodes are present and may be undertaken repeatedly to monitor the growth or shrinkage of nodules. While this technique is important for finding cancers, it cannot be used as a diagnostic tool. Instead, a thyroid fine needle biopsy can test whether thyroid nodules have abnormal cells by sticking a tiny needle into the gland and taking out fluid and cells. Finally, a physical exam can be performed quickly and efficiently by your health care provider, looking for abnormal size and shape of the thyroid.

Managing a thyroid disorder

For some thyroid disorders, the gland can return to normal function with minimal interventions. For roughly 5% of Hashimoto’s disease, decreasing the activity of TSH can promote normal function. Post-partum thyroid disorders are also likely in 70% of cases to go back to normal within a year, and subacute thyroid disorders – where hormone levels are altered only slightly – are nearly at a 100% recovery rate. Thyroid disorders caused by too much or too little iodine can become normal when iodine intake is rectified, as also seen in drug-induced thyroid disorders. However, 95% of Hashimoto’s disease cases will develop lifelong thyroid dysfunction and require treatment with T4. The dose of T4 given depends on age; weight; health status; and whether the person has any gluten sensitivity, is taking other medications or is pregnant.

Sometimes, people on replacement T4 doses can also have persistently raised TSH. This can be due to many factors, such as not taking the correct dosage or amount; interactions with other drugs; thyroid dysfunction due to a second cause; pregnancy; or, importantly for women, post-menopausal hormone treatment. Having a thorough history of your health and medications is crucial for accurately rectifying thyroid function. Graves’ disease can be treated with antithyroid drugs, radioactive iodine therapy or surgery where part of or the entire thyroid is removed. Surgery is a last-ditch effort, with medications being the first line of therapy. Once treatment has begun, thyroid tests are done every four to six weeks until normal thyroid function is restored.

Medications can come with side effects of skin reactions, joint pain, and stomach upsets. Particularly important, agranulocytosis is a blood disorder where white blood cells attack the immune system – heralded by fever and sore throat, it is vital to see a doctor immediately if these symptoms occur. The most common side effect – particularly of T4 treatments – is hair loss, particularly in the first few months. Other potential side effects include:

• Increased sweating
• Mood swings or irritability
• Nervousness/anxiety and potential panic attacks
• Fatigue
• Headaches
• Hot flashes
• Tremors and palpitations

Sometimes these are easily fixed, with dose adjustments and medications changes; but these can also be due secondary disorders that need addressing immediately.

Finally, keep your eyes open when it comes to the purported benefits of taking additional T3 or ‘natural’ thyroid-specific medications and supplements. While sometimes additional T3 can ease thyroid disorders, this has yet to have proven benefits. Additionally, many supplements and natural treatments claim to support thyroid health – but are laced with thyroid hormones that aren’t listed on the label. Adding these to your thyroid drugs can mean you end up taking too much thyroid medication. Indeed, in a 2013 study in Germany, 9 of the 10 top-selling thyroid supplemental natural products were found to be laced with T3, T4 or both Supplements that contain seaweed or kelp can also interact dangerously with medications due to high iodine levels.

Now what?

A thyroid disorder can be incredibly disrupting to women in an already transitional time of life. The symptoms can not only decrease quality of life – they can be life-threatening. Changes in women’s hormones and additional stresses in life can interact with the thyroid to bring on hormone alterations that precede disorders. If any of the symptoms or medication side effects mentioned here ring a bell, see your doctor immediately. A good practitioner will never dismiss these issues and will understand that women in particular are vulnerable to thyroid dysfunction. Keeping a thorough medical history and maintaining overall health check-ups is the best way to identify any thyroid changes early and develop the most appropriate treatment plan.

Disclaimer: This article provides general information only, and does not constitute health or medical advice. If you have any concerns regarding your health, seek immediate medical attention.