What is a Thyroid Gland?

The thyroid gland is a butterfly-shaped organ located in the front of your neck, wrapped around your windpipe (trachea). Hormones are secreted to control a variety of metabolic processes, including growth and energy expenditure. The metabolism will be altered whether the thyroid gland is hyperactive or sluggish.

How does a Thyroid Gland Function?

The thyroid gland converts iodine, which is obtained through diet, into thyroid hormones such as thyroxine (T4) and triiodothyronine (T3). The only cells in the body that can absorb iodine are thyroid cells. T3 and T4 are produced when iodine and the amino acid tyrosine are combined in these cells. The thyroid hormones T3 and T4 are subsequently released into the bloodstream and carried throughout the body, where they regulate metabolism.

What Is Hyperthyroidism?

Hyperthyroidism is a condition where the thyroid gland is hyperactive and hence produces an excessive amount of thyroid hormone. Hyperthyroidism can be caused by either the presence of autoimmune antibodies, such as that seen in Graves Disease, or a toxic nodule that is secreting an excessive amount of thyroid hormone.

What Are Some Common Symptoms of Hyperthyroidism?

Hyperthyroidism is characterised by excessive production of thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3), which can lead to various symptoms. These symptoms can vary in severity and may include:

Weight Loss

Unexplained and rapid weight loss, even with an increased appetite, is a common symptom of hyperthyroidism.

Increased Appetite

People with hyperthyroidism often experience increased hunger and appetite, which can contribute to weight loss.

Heart Palpitations

Excess thyroid hormones can lead to a faster heart rate and palpitations. This can make the heart feel like it’s racing or skipping beats.

Increased Heart Rate

There is an overall increase in heart rate, even at rest, along with palpitations.

Heat Intolerance

Individuals with hyperthyroidism often feel excessively hot or sweat more than usual, even in cooler temperatures.


Fine trembling of the hands and fingers can occur due to the stimulating effects of excess thyroid hormones on the nervous system.

Nervousness and Anxiety

Hyperthyroidism can lead to feelings of restlessness, anxiety, and irritability.

Difficulty Sleeping

Insomnia or trouble falling asleep can result from the heightened metabolic state caused by excess thyroid hormones.


Despite the increased metabolic rate, some individuals experience fatigue due to the strain on the body’s systems.

Muscle Weakness

Muscle weakness, especially in the upper arms and thighs, can occur.

Changes in Bowel Habits

Hyperthyroidism can lead to increased frequency of bowel movements or diarrhoea.

Excessive Sweating

Sweating more than usual, even without physical exertion, is a common symptom.

Fine Hair and Brittle Nails

Hair might become thinner and more prone to breakage, and nails can become brittle.

Bulging Eyes (Exophthalmos)

In Graves’ disease, a common cause of hyperthyroidism, the eyes might appear to bulge due to inflammation and tissue changes around the eyes.

Skin Changes

The skin might become thinner, more sensitive, and prone to itching.

Menstrual Irregularities

Women with hyperthyroidism may experience changes in their menstrual cycles, including lighter or irregular periods.

Enlarged Thyroid Gland (Goiter)

In some cases, the thyroid gland might become enlarged and visible as a swelling in the neck.

How Is Hyperthyroidism Diagnosed?

Hyperthyroidism is typically diagnosed through medical history assessment, physical examination, and laboratory tests.
  • TSH Test – This test measures the level of thyroid-stimulating hormone. In most cases of hyperthyroidism, TSH levels are low because the excess thyroid hormones inhibit the release of TSH from the pituitary gland.
  • Free T4 Test – This measures free thyroxine (T4), the main thyroid hormone produced by the thyroid gland.
  • Free T3 Test – This measures free triiodothyronine (T3), the more active thyroid hormone.

Additional Tests

Depending on the situation, your doctor might recommend additional tests to evaluate the underlying cause of hyperthyroidism further:
  • Thyroid Antibody Tests – These tests, including anti-thyroid peroxidase antibodies (TPOAb) and anti-thyroglobulin antibodies (TgAb), can help identify autoimmune causes like Graves’ disease.


In some cases, imaging studies such as ultrasound might be used to assess the thyroid gland’s size and structure and identify any nodules or abnormalities.

What Are the Health Complications of an Untreated Hyperthyroidism?

If left untreated, hyperthyroidism can lead to various health complications, some of which can be serious or even life-threatening. Addressing hyperthyroidism with proper medical treatment is crucial to prevent these potential complications. Some of the complications that can arise from untreated hyperthyroidism include:

Heart Problems

Arrhythmias An irregular heart rhythm, such as atrial fibrillation, can result from the increased heart rate and stimulation caused by excess thyroid hormones. This increases the risk of blood clots and stroke. Heart Failure Over time, the strain on the heart due to persistent high heart rate and increased workload can lead to heart muscle weakness and heart failure.


Excess thyroid hormones can lead to accelerated bone loss, increasing the risk of osteoporosis and fractures.

Thyroid Storm

A thyroid storm can occur in severe cases of hyperthyroidism, particularly in conditions like Graves’ disease. This rare but life-threatening condition is characterised by extremely high levels of thyroid hormones, leading to severe symptoms such as fever, rapid heart rate, confusion, agitation, and even coma.

Eye Complications (Graves' Disease)

In Graves’ disease, an autoimmune cause of hyperthyroidism, eye complications can arise. These include bulging eyes (exophthalmos), double vision, eye pain, and vision loss in extreme cases.

Psychological and Emotional Issues

Untreated hyperthyroidism can contribute to increased anxiety, irritability, and mood disturbances.

Weight Loss and Muscle Wasting

Continued weight loss, muscle wasting, and weakness can decrease overall health and vitality.

Gastrointestinal Problems

Persistent diarrhoea and gastrointestinal symptoms can lead to nutritional deficiencies and electrolyte imbalances.

Impaired Immune Function

Hyperthyroidism can weaken the immune system’s response to infections, making the individual more susceptible to illnesses.

Complications During Pregnancy

Untreated hyperthyroidism during pregnancy can lead to complications such as preeclampsia, preterm birth, and low birth weight.

Menstrual and Fertility Issues

Irregular menstrual cycles, decreased fertility, and problems related to hormone imbalances can occur in women with untreated hyperthyroidism.

Fatigue and Weakness

While it might seem counterintuitive due to the increased metabolic rate, prolonged hyperthyroidism can lead to persistent fatigue and muscle weakness.

Worsening of Underlying Conditions

If an individual already has other medical conditions, untreated hyperthyroidism can exacerbate these conditions.

What Are the Different Treatment Options for Hyperthyroidism?

The treatment approach for hyperthyroidism depends on the underlying cause, the severity of the condition, the patient’s age, overall health, and preferences. Here are the different treatment options available:

Antithyroid Medications

  • Carbimazole or Thiamazole or Propylthiouracil (PTU) – These medications inhibit the production of thyroid hormones by interfering with the thyroid gland’s ability to use iodine.
  • Beta-Blockers Medications like propranolol and atenolol can help alleviate symptoms such as rapid heart rate, palpitations, and tremors. They don’t treat the underlying cause but provide relief from some of the uncomfortable symptoms.

Radioactive Iodine Therapy

Radioactive iodine (RAI) is taken orally and is absorbed by the thyroid gland. The radiation destroys thyroid cells, reducing hormone production. This treatment is effective for most causes of hyperthyroidism but can result in hypothyroidism over time, requiring lifelong thyroid hormone replacement.

Thyroid Surgery (Thyroidectomy)

Surgical removal of part or all of the thyroid gland is an option, particularly for individuals who can’t tolerate antithyroid medications or are not candidates for radioactive iodine treatment. Total thyroidectomy eliminates the possibility of recurrent hyperthyroidism but requires lifelong thyroid hormone replacement therapy.

Medication Adherence

If you’re prescribed antithyroid medications, take them as directed by your doctor to help regulate thyroid hormone levels.

Communication with Doctor

Keep an open line of communication with your doctor about your symptoms, concerns, and any changes you experience.

Eye Care (Graves' Disease)

If you have Graves’ disease and are experiencing eye symptoms, work with your healthcare team to manage them. Lubricating eye drops and sunglasses can help alleviate discomfort.

Dr. Cho Li Wei 朱丽薇医生

Consultant Endocrinologist
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