What is hyperthyroidism?

Hyperthyroidism, or an overactive thyroid, is when the gland produces and releases too much thyroid hormone into the bloodstream, speeding up the body’s metabolism. Hyperthyroidism is more common in women and those with a family history of autoimmune thyroid diseases.¹

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How common is it?

The most common causes of hyperthyroidism are Graves’ disease (a form of autoimmune thyroid disease) and toxic thyroid nodule(s). Around 90% of patients with thyroid disorders in Singapore suffer from hyperthyroidism, with Chinese women being at higher risk for developing this disorder as a result of Graves’ disease.² 

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Symptoms of hyperthyroidism

If you suffer from hyperthyroidism then you are likely to notice you have lost weight, even if you are eating normally or even more than before. You may also feel a fast heart rate.¹

Watch out for the following symptoms:^1,3

• Fast heart rate (often more than 100 beats per minute)
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• Nervousness and/or irritability
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• Weight loss without dietary changes
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• Prominent, staring eyes (typical for Graves’ disease)
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• Muscle weakness, especially of the upper arms and thighs
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• Heat intolerance and increased sweating
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• Frequent bowel movements
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• Lighter or less frequent menstrual periods
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• Trembling hands
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• Fine brittle hair
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It is important that symptoms of hyperthyroidism are not left untreated as serious complications can occur. In addition, hyperthyroidism increases the risk for osteoporosis (brittle bones) and bone fractures, with women who have gone through menopause having an even greater risk.⁴

Symptoms alone do not reliably tell whether you have hyperthyroidism. This is particularly true for elderly patients who may not present with much symptoms. A physical examination and blood tests are needed to diagnose hyperthyroidism.

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Who is at risk?

• Women between 20‒50 years old are more prone to developing hyperthyroidism due to Graves’ disease^{5
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• People who have relatives with autoimmune thyroid or other autoimmune disorders^{5,6
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• People with autoimmune disorders, such as type 1 diabetes<sup>6
  
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How thyroid hormones impact your heart

The heart is a major target of thyroid hormones. Any change in thyroid hormone levels will affect the heart.

Too much thyroid hormone as a consequence of an overactive thyroid (hyperthyroidism) may cause the heart to work harder and faster, causing:^6,7

• Increased heart rate
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• Irregular heartbeat (atrial fibrillation)
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• Increase in blood pressure
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• Heart failure, especially in those with pre-existing heart conditions
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Left untreated, an overactive thyroid can cause heart disease or worsen a pre-existing heart problem.⁹ Elderly patients are especially vulnerable to the effect of high thyroid hormones on the heart.

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Diagnosing hyperthyroidism

Thyroid dysfunction can be confirmed by your doctor through a simple blood test to check the level of thyroid-stimulating hormone (TSH) and thyroid hormones in your blood.¹

If you are concerned that you could be suffering from problems with your thyroid gland, please discuss this with your doctor. To aid your consultation, download our Wellbeing Diary  to help you keep a check of the symptoms you are experiencing or try the Symptom Checker.
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How is hyperthyroidism treated?

Depending on the cause of hyperthyroidism, your age and health status, and how overactive your thyroid is, your doctor will choose a treatment option that is best suited for you.

Anti-thyroid drugs prevent the thyroid gland from producing new thyroid hormones.¹ Alternatively the thyroid tissue can be destroyed using radioactive iodine or by surgically removing parts of or the whole thyroid gland.¹ Hypothyroidism may develop after radioactive iodine treatment and surgery. This can be treated with thyroid hormone replacement therapy.¹

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Summary

• Hyperthyroidism is a condition in which the thyroid gland produces excessive thyroid hormones
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• The most accurate way of diagnosing hyperthyroidism is through a blood test known as thyroid function test
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• Treatment of hyperthyroidism depends on the cause of hyperthyroidism, your age and health status, and how overactive your thyroid is.