Key points
- Hyperthyroidism means the thyroid makes too much hormone. Graves' disease, an autoimmune condition, is the most common cause.
- It shows up as a low TSH with high free T4 or T3. Other tests find the cause, which decides the treatment.
- The three main treatments are antithyroid tablets, radioactive iodine and surgery. Each has trade-offs to discuss with your doctor.
- Sore throat or fever while on antithyroid tablets needs an urgent blood test. Untreated hyperthyroidism strains the heart and bones.
Hyperthyroidism is less common than an underactive thyroid, but it is often more dramatic. People describe feeling “wired”, unable to sit still, sweating through Indian summers far more than usual, or noticing their clothes getting loose without trying. Some put it down to stress or a busy job for months. The good news is that it is very treatable.
What hyperthyroidism is
In hyperthyroidism, the thyroid makes more hormone than the body needs. Because thyroid hormones set the pace of metabolism, everything speeds up: heart rate, digestion, energy use and nerves. The pituitary gland senses the high levels and switches off TSH, so a low TSH is usually the first clue. Doctors sometimes use the broader word “thyrotoxicosis” for any state of too much thyroid hormone, including from too high a dose of thyroid tablets.
Symptoms
- Fast or irregular heartbeat, palpitations
- Weight loss despite eating well or more
- Feeling hot, sweating, intolerance of heat
- Shaky hands (tremor), anxiety, irritability, poor sleep
- Frequent loose motions
- Muscle weakness, especially climbing stairs
- Lighter or irregular periods
- A swelling in the neck (goitre)
- Gritty, bulging or watering eyes (in Graves' disease)
Older adults may have few of these and instead notice tiredness, weight loss or an irregular heartbeat called atrial fibrillation.
Causes
| Cause | What happens | Typical course |
|---|---|---|
| Graves' disease | Antibodies switch the thyroid on continuously | Most common cause; can settle with treatment but may come back |
| Toxic nodules | One or more lumps in the thyroid make hormone on their own | More common in older adults; usually does not settle on its own |
| Thyroiditis | Inflammation releases stored hormone (after pregnancy, after a viral illness, or painless) | Often temporary, sometimes followed by an underactive phase |
| Too much thyroid medicine or iodine | Excess hormone or iodine from tablets, supplements or some medicines | Settles when the cause is corrected |
Finding the cause matters, because thyroiditis usually needs only symptom relief, while Graves' disease and nodules need treatment of the thyroid itself.
Thyroid eye disease
Some people with Graves' disease develop eye problems: grittiness, redness, puffy lids, a staring look, bulging eyes or double vision. Smoking makes thyroid eye disease much more likely and much worse, so stopping smoking is one of the most important things you can do. Mild symptoms often improve with lubricating eye drops. Pain, double vision or any change in your sight needs an eye specialist promptly.
Tests
- TSH, free T4 and free T3 confirm whether thyroid hormone is high. Our guide to thyroid tests explained covers how to read them.
- TSH receptor antibodies (TRAb) confirm Graves' disease.
- A thyroid scan (radioactive iodine uptake or technetium scan) shows whether the gland is overactive overall, has hot nodules, or is inflamed. It is not done in pregnancy or while breastfeeding.
- An ultrasound looks at nodules and blood flow.
- Blood count and liver tests are usually checked before starting antithyroid tablets.
Treatment options
Many people first get a beta-blocker, a medicine that calms the racing heart and tremor while the main treatment takes effect. The 2016 American Thyroid Association guideline describes three ways to treat the thyroid itself. Your doctor will talk through which suits you, considering the cause, your age, pregnancy plans, eye disease and your preferences.
| Option | How it works | Things to consider |
|---|---|---|
| Antithyroid tablets (carbimazole or methimazole; propylthiouracil in some situations) | Block the making of thyroid hormone | Usually the first choice in India for Graves'; often taken for 12 to 18 months; Graves' can return after stopping; needs regular blood tests |
| Radioactive iodine | A capsule or drink that is taken up by the thyroid and slowly shrinks it | Effective and widely used; usually leads to an underactive thyroid needing lifelong thyroxine; not used in pregnancy or breastfeeding, and pregnancy must be avoided for a period afterwards; can worsen eye disease in some people |
| Surgery (thyroidectomy) | Removes all or part of the gland | Quick, definite fix, useful for large goitres or suspicious nodules; lifelong thyroxine afterwards; small risks to the voice and calcium levels |
Warning signs on antithyroid tablets
Antithyroid tablets are safe for most people, but rarely they lower the white blood cells that fight infection (agranulocytosis) or affect the liver. If you develop a sore throat, mouth ulcers or fever, stop and get an urgent blood count before taking the next tablet, and tell the doctor you are on carbimazole or methimazole. Yellow eyes, dark urine or severe itching also need urgent attention. Ask your doctor to explain these signs when you start, and keep a note of them.
Long-term health
Untreated or poorly controlled hyperthyroidism can cause an irregular heartbeat (atrial fibrillation), heart failure, thinning bones and, in pregnancy, problems for mother and baby. Once controlled, most people do very well. Follow-up blood tests continue for years, because Graves' disease can relapse and treatments often lead to an underactive thyroid. If you are planning a pregnancy, discuss it before choosing treatment; see our guide to thyroid and pregnancy.
When to see a doctor
- You have a racing heart, tremor, weight loss or heat intolerance that has lasted more than a couple of weeks.
- Sore throat, mouth ulcers or fever while on antithyroid tablets: get an urgent blood count today.
- Eye pain, double vision or any loss of vision.
- Chest pain, breathlessness, fainting or a very fast, irregular pulse: call 112.
- High fever, confusion, vomiting or extreme agitation with known hyperthyroidism: call 112. This can be a thyroid storm, a medical emergency.
Questions to ask your doctor
- What is causing my overactive thyroid, and how sure are we?
- Which treatment do you recommend for me, and why?
- How often will I need blood tests?
- What warning signs should make me stop my tablets and call you?
- How does treatment fit with my plans for pregnancy?
Frequently asked questions
What is the most common cause of hyperthyroidism?
Graves' disease, an autoimmune condition in which antibodies switch the thyroid on, is the most common cause. Toxic nodules and thyroiditis are other common causes.
Can hyperthyroidism go away on its own?
Some types, such as thyroiditis after pregnancy or a viral illness, often settle on their own. Graves' disease and toxic nodules usually need treatment, though Graves' can go into remission after a course of antithyroid tablets.
Is radioactive iodine treatment safe?
It is a long-established and effective treatment. It usually leads to an underactive thyroid, which is then treated with thyroxine. It is not used in pregnancy or breastfeeding, and your doctor will explain precautions afterwards.
Why did my doctor ask me to report a sore throat?
Rarely, antithyroid tablets lower the white blood cells that fight infection. A sore throat, mouth ulcers or fever can be the first sign, so you need an urgent blood count before taking more tablets.
Sources
- Ross DS, et al. 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis. Thyroid 2016;26(10):1343–1421.
- Unnikrishnan AG, et al. Prevalence of hypothyroidism in adults: an epidemiological study in eight cities of India. Indian J Endocrinol Metab 2013;17(4):647–652.
This article is general information for adults in India and is not a diagnosis or a treatment plan. Always discuss results and any changes with your own doctor. Read our editorial policy.