What Is Hyperthyroidism?
What Is Hyperthyroidism? Symptoms, Tests and Treatment
Hyperthyroidism occurs when the thyroid gland produces too much thyroid hormone. Excess levels of these hormones can speed up many bodily functions. Thyrotoxicosis is a broader term describing excess thyroid hormone in the blood; it can also occur when the gland is not producing new hormone, such as when thyroiditis causes stored hormones to be released into the bloodstream. Identifying the cause is therefore important when choosing treatment.
What causes hyperthyroidism?
The main conditions that can lead to hyperthyroidism are:
- Graves' disease: An autoimmune disease in which the immune system causes the thyroid gland to become overactive.
- Toxic nodule or toxic multinodular goitre: Excess hormone production by one or more nodules in the thyroid.
- Thyroiditis: The release of stored hormones into the bloodstream due to inflammation of the thyroid gland. Some types of thyroiditis may be temporary.
- Taking excessive amounts of medicines containing thyroid hormone.
Not all causes are managed with the same treatment. For example, medicines that reduce hormone production may not be appropriate when elevated hormone levels are due to thyroiditis.
What are the symptoms?
Symptoms of hyperthyroidism can vary from person to person. Possible symptoms include:
- Palpitations or a rapid heartbeat
- Trembling hands
- Heat intolerance and sweating
- Weight loss despite an increased appetite
- Restlessness, anxiety or difficulty sleeping
- Muscle weakness and fatigue
- Frequent bowel movements
- Changes in menstrual patterns
- Enlargement of the thyroid gland in the neck
Graves' disease may also cause dry eyes, eye discomfort or prominent eyes. As these symptoms can also occur with other health conditions, a medical assessment and appropriate tests are needed for diagnosis.
How is hyperthyroidism diagnosed?
Assessment usually begins with a TSH test. TSH is usually low in hyperthyroidism; free T4 (FT4) and free T3 (FT3) levels help assess the diagnosis and the degree of hormone excess. In some people, T3 may be elevated even when FT4 is normal. Test results should be interpreted alongside symptoms, examination findings and any medicines being taken. A diagnosis can be made by checking hormone levels using a thyroid function test —a blood test that measures these levels.
To identify the cause, the doctor may request antibody tests such as TSH receptor antibodies (TRAb/TSI). Depending on the findings, a thyroid ultrasound or other imaging investigations may also be needed. Not every patient needs all of these tests.
How is hyperthyroidism treated?
Treatment is planned according to the cause and severity of the elevated hormone levels, the person's age and other health conditions. Options include antithyroid medicines, medicines to help control symptoms, radioactive iodine therapy or surgery. Not every treatment is suitable for every cause; ongoing monitoring involves blood tests.
The doctor should be informed if you are pregnant or planning a pregnancy. Radioactive iodine therapy is not used during pregnancy; the choice of medication and follow-up can be planned jointly with endocrinology and obstetrics and gynaecology specialists.
Which blood tests are used for hyperthyroidism?
Depending on the doctor's assessment, TSH, FT4 and FT3 tests may be requested, along with thyroid antibody tests in some cases. You can provide a sample at Wellcare Laboratories for blood tests that assess thyroid function. The tests required are determined by the clinical situation.
Frequently asked questions
Does a low TSH level definitely mean I have hyperthyroidism?
No. A low TSH level should be assessed alongside thyroid hormone tests and clinical findings. In some cases, a low TSH level may have a cause other than hyperthyroidism.
Are hyperthyroidism and thyrotoxicosis the same thing?
Not exactly. Hyperthyroidism means that the thyroid gland produces too much hormone. Thyrotoxicosis describes excess thyroid hormone in the blood due to various causes.
What can happen if hyperthyroidism is left untreated?
Hyperthyroidism that remains uncontrolled for a long time can affect heart rhythm and bone health. Consult a healthcare professional if you have palpitations, a rapid pulse or a noticeable worsening of your condition. Seek emergency medical help if a very rapid heartbeat is accompanied by a high fever, confusion or severe vomiting.