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Hyperthyroidism: causes, treatment, and more

Hyperthyroidism is a medical condition characterized by the overactivity of the thyroid gland, which results in the excessive production of thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3). These hormones play a crucial role in regulating the body's metabolism, so when they are produced in excess, it can lead to a variety of symptoms and health issues.

Hyperthyroidism symptoms

Common symptoms of hyperthyroidism include:

  • Weight loss

  • Nervousness and anxiety

  • Increased heart rate

  • Sweating and heat sensitivity

  • Tremors

  • Fatigue

  • Thyroid enlargement

  • Eye problems


While the core symptoms are similar, some studies suggest that women may experience certain gender-specific symptoms, including:


Hyperthyroidism causes

  • Graves' disease: This autoimmune disorder is the most prevalent cause of hyperthyroidism. In Graves' disease, the body's immune system mistakenly produces antibodies that stimulate the thyroid to produce excess hormones. It often results in an enlarged thyroid (goiter) and can affect both men and women.

  • Toxic multinodular goiter: In this condition, multiple nodules (lumps) form in the thyroid gland, which can produce hormones independently, leading to excessive thyroid hormone production. It is more common in women and often occurs in older individuals.

  • Thyroiditis: Thyroiditis refers to the inflammation of the thyroid gland. In some cases, this inflammation can cause the release of excess thyroid hormones into the bloodstream. It can be triggered by viral infections, certain medications, or autoimmune conditions.

  • Excessive iodine intake: Consuming an excessive amount of iodine, whether through diet or medication, can lead to hyperthyroidism. This is more common in individuals who already have an underlying thyroid condition.

  • Toxic adenomas: Adenomas are non-cancerous tumors that develop in the thyroid gland. Some adenomas produce thyroid hormones autonomously, leading to hyperthyroidism.

  • Secondary causes: In rare cases, problems with the pituitary gland or hypothalamus can lead to an overproduction of thyroid-stimulating hormone (TSH), which, in turn, stimulates the thyroid gland to produce more hormones.


How do you diagnose hyperthyroidism?

  • A primary care provider or endocrinologist will start by conducting a thorough medical history and physical examination. During this assessment, they will inquire about your symptoms, medical history, family history of thyroid conditions, and any medications or supplements you are taking.

  • The primary diagnostic tool for hyperthyroidism involves blood tests to measure the levels of specific thyroid hormones. These tests typically include:

    • TSH (Thyroid-Stimulating Hormone) Test: Low levels of TSH are usually a strong indicator of hyperthyroidism. TSH is produced by the pituitary gland and stimulates the thyroid to produce thyroid hormones. In hyperthyroidism, the pituitary gland reduces TSH production in response to elevated thyroid hormone levels.

    • Free T4 (Thyroxine) and Free T3 (Triiodothyronine) Tests: These tests measure the levels of active thyroid hormones in the bloodstream. In hyperthyroidism, both Free T4 and Free T3 levels are typically elevated.

    • Thyroid Antibody Tests: If an autoimmune condition like Graves' disease is suspected, antibody tests, such as anti-TSH receptor antibodies, may be performed to confirm the diagnosis.

  • In some cases, your doctor may recommend a radioactive iodine uptake (RAIU) test to assess how much iodine your thyroid gland absorbs and to identify any areas of increased activity. This can help distinguish between different causes of hyperthyroidism.

  • A thyroid ultrasound may be used to visualize the structure of the thyroid gland and identify any nodules or enlargement. It can be particularly helpful in cases where thyroiditis or nodular goiter is suspected.

  • If thyroid nodules are detected and there is concern about cancer, a fine needle aspiration (FNA) biopsy may be performed to obtain a tissue sample for further analysis.

  • Depending on the clinical presentation and test results, additional tests, such as a thyroid scan using radioactive iodine, may be ordered to provide more detailed information about the thyroid's function.


It's important to differentiate hyperthyroidism from other conditions that may have similar symptoms, such as anxiety disorders or other medical conditions. Once the diagnosis is confirmed, a St. Luke’s Health endocrinologist will work with you to develop an appropriate treatment plan. 

Treating hyperthyroidism

The treatment for hyperthyroidism depends on the underlying cause and the severity of the condition. Here are the primary treatment options for hyperthyroidism:

  • Antithyroid medications:

    • Propylthiouracil (PTU) and Methimazole (Tapazole): These medications work by reducing the production of thyroid hormones. They are often the first line of treatment for hyperthyroidism, especially in cases of Graves' disease. PTU is sometimes preferred during the first trimester of pregnancy.

    • Beta-blockers: These drugs, such as propranolol, can help manage the symptoms of hyperthyroidism, such as rapid heart rate, tremors, and anxiety, while the underlying condition is being treated. They do not, however, address the root cause.

  • Radioactive iodine therapy involves the oral ingestion of radioactive iodine, which is selectively taken up by the overactive thyroid cells. The radiation damages or destroys these cells, leading to a reduction in thyroid hormone production. This therapy is often used for individuals with Graves' disease or toxic nodular goiter.

  • In cases where medication and radioactive iodine therapy are not suitable or have not been successful, surgical removal of part or all of the thyroid gland may be necessary. This is called a thyroidectomy. It's typically recommended in cases of large goiters, thyroid cancer, or when other treatments are contraindicated.

Consult with your endocrinologist before making significant lifestyle modifications to your diet or exercise routine, as they can provide personalized recommendations based on your specific condition and treatment plan.

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