Quick answer. Hyperthyroidism means an overactive thyroid producing too much hormone. In Singapore, Graves’ disease (autoimmune) causes around 70% of cases; other causes include toxic nodules and toxic multinodular goitre. Typical symptoms are unintentional weight loss, palpitations, heat intolerance, sweating, hand tremor, anxiety, frequent bowel movements and, in Graves’ disease, eye changes (bulging, gritty or double vision). Diagnosis uses blood tests showing low TSH with high thyroid hormones, plus tests for the cause. Treatments are anti-thyroid drugs (such as carbimazole), radioactive iodine, or surgery. Thyroid eye disease may need separate care; smoking worsens it. Untreated severe hyperthyroidism can rarely trigger a dangerous thyroid storm.
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Hyperthyroidism, or an overactive thyroid, happens when the thyroid gland produces too much thyroid hormone, speeding up many of the body’s processes. In Singapore, the commonest cause is Graves’ disease, an autoimmune condition in which the immune system stimulates the thyroid; it accounts for around 70% of cases. Other causes include a single overactive (toxic) nodule, a toxic multinodular goitre, and excess iodine.
This guide focuses on overactive thyroid and Graves’ disease specifically, rather than thyroid conditions in general. It covers the typical symptoms, how the diagnosis is made, the treatment options available in Singapore (anti-thyroid medication, radioactive iodine and surgery), and thyroid eye disease, which is closely linked to Graves’ disease. With proper treatment, most people with hyperthyroidism do very well.
At a glance
| Aspect | Details | Notes |
|---|---|---|
| Commonest cause | Graves' disease (autoimmune) | About 70% of cases in Singapore |
| Other causes | Toxic nodule, toxic multinodular goitre, excess iodine | Cause guides treatment choice |
| Key symptoms | Weight loss, palpitations, heat intolerance, tremor, anxiety | Plus eye changes in Graves' disease |
| Diagnosis | Blood tests: low TSH, high T4/T3, plus tests for the cause | Imaging or antibodies may be added |
| Treatments | Anti-thyroid drugs, radioactive iodine, surgery | Choice depends on cause and patient factors |
| Eye disease | Thyroid eye disease (bulging, gritty, double vision) | Smoking worsens it; may need eye specialist |
Symptoms of an overactive thyroid
Because thyroid hormone affects nearly every organ, hyperthyroidism can cause a wide range of symptoms, which may come on gradually:
- Unintentional weight loss despite a normal or increased appetite
- Palpitations or a fast, sometimes irregular heartbeat
- Heat intolerance and excessive sweating
- Hand tremor, anxiety, restlessness and difficulty sleeping
- Frequent bowel movements or loose stools
- Muscle weakness, tiredness, and lighter or less frequent periods
- In Graves’ disease, eye changes such as bulging, gritty or watery eyes, light sensitivity, or double vision; some people develop a visible goitre
Severe, untreated hyperthyroidism can rarely escalate to a thyroid storm, a medical emergency with high fever, racing heart and confusion that needs urgent hospital care.
Causes and how it is diagnosed
The main causes of hyperthyroidism are Graves’ disease (autoimmune, the commonest in Singapore at around 70%), a toxic nodule, a toxic multinodular goitre, and excess iodine intake. Some causes, such as thyroiditis, are temporary.
Diagnosis starts with blood tests: a low TSH with high thyroid hormones (T4 and/or T3) confirms an overactive thyroid. To find the cause, your doctor may order thyroid antibodies (raised in Graves’ disease), an ultrasound, or a radioactive iodine uptake scan that shows how the gland is functioning. Identifying the cause is important because it guides which treatment is most suitable.
Treatment options in Singapore
There are three main treatments, often used alongside a beta-blocker (such as propranolol) to ease palpitations and tremor while other treatments take effect:
- Anti-thyroid drugs (commonly carbimazole, also thiamazole or propylthiouracil): tablets that reduce hormone production, usually taken for 12-18 months. They can have side effects, and a rare but serious one is a drop in white blood cells, so seek urgent care if you develop a high fever or severe sore throat.
- Radioactive iodine (RAI): a single oral dose that is taken up by the thyroid and gradually shrinks it. It is effective and widely used, but most people eventually become underactive (hypothyroid) and need lifelong thyroid hormone replacement. RAI is avoided in pregnancy and breastfeeding, and pregnancy must be avoided for several months afterwards.
- Surgery (thyroidectomy): removal of part or all of the thyroid, considered for a large goitre, suspected cancer, or when planning pregnancy. Medication is used first to stabilise hormone levels before surgery.
The best option depends on the cause, your age, whether you plan pregnancy, the presence of eye disease, and your preferences.
Thyroid eye disease (Graves' eye disease)
Thyroid eye disease (TED) is inflammation of the tissues and muscles around the eyes, most often seen in Graves’ disease. Symptoms include bulging or prominent eyes, redness, grittiness, watering, light sensitivity, and in more severe cases double vision or reduced vision.
- Stop smoking: smoking strongly worsens TED and reduces how well treatment works
- Radioactive iodine can sometimes worsen active eye disease, especially in smokers, so the treatment choice is considered carefully; a short course of steroids may be given around RAI in some cases
- Mild TED may need only lubricating eye drops and monitoring; moderate to severe disease may require steroids, an ophthalmologist’s care, or specialist treatments
Seek urgent eye assessment for sudden loss of vision, worsening colour vision, or severe eye pain.
Living with hyperthyroidism and follow-up
With treatment, most people with hyperthyroidism return to normal thyroid function and feel well. Important points for ongoing care:
- Regular blood tests to adjust medication and check for under- or over-treatment
- After radioactive iodine or surgery, watch for symptoms of an underactive thyroid (tiredness, weight gain, cold intolerance), as many people will need lifelong thyroid hormone replacement
- Tell your doctor if you are planning pregnancy, as this affects the choice and timing of treatment
- Do not stop anti-thyroid medication suddenly without advice, as hyperthyroidism can return
Care is usually led by an endocrinologist, with input from eye specialists for thyroid eye disease and surgeons where surgery is planned. Costs vary by treatment and setting.
Related guides
- Best Endocrinology & Diabetes Clinics in Singapore — our editorial shortlist
- endocrinology & diabetes clinics directory
- Gestational diabetes
- Thyroid nodules & goitre
- Diabetic complications
Sources
- SingHealth – Hyperthyroidism
- HealthXchange – Hyperthyroidism (Overactive Thyroid): Causes and Symptoms
- SGH – Guide to Radioactive Iodine Treatment for Hyperthyroidism
- American Thyroid Association – Thyroid Eye Disease and Radioactive Iodine
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