From the Guidelines
Hyperthyroidism is primarily caused by Graves disease, Hashimoto thyroiditis, and functional thyroid nodules, as identified in a 2015 study published in the Annals of Internal Medicine 1. The causes of hyperthyroidism can be broken down into several key categories, including:
- Graves disease, an autoimmune disorder that leads to overproduction of thyroid hormones
- Hashimoto thyroiditis, an autoimmune condition that can cause thyroid inflammation and lead to hyperthyroidism
- Functional thyroid nodules, which can produce excess thyroid hormones Other risk factors for hyperthyroidism include female sex, advancing age, black race, low iodine intake, personal or family history of thyroid disease, and ingestion of iodine-containing drugs, such as amiodarone 1. It is essential to note that the treatment of hyperthyroidism depends on the underlying cause, with antithyroid medications, such as methimazole, or nonreversible thyroid ablation therapy, including radioactive iodine or surgery, being common treatment options 1. The diagnosis of hyperthyroidism typically involves a serum TSH test, with multiple tests done over a 3- to 6-month interval to confirm or rule out abnormal findings, and follow-up testing of serum T4 levels to differentiate between subclinical and overt thyroid dysfunction 1.
From the Research
Causes of Hyperthyroidism
- The most common cause of hyperthyroidism is Graves' disease, an autoimmune disorder associated with circulating immunoglobulins that bind to and stimulate the thyrotropin (TSH) receptor, resulting in sustained thyroid overactivity 2, 3, 4.
- Other causes of hyperthyroidism include toxic nodular goiters, which cause hyperthyroidism due to autonomous hyperfunctioning of localized areas of the thyroid 2, 3, 5.
- Toxic adenoma and toxic multinodular goiter are also recognized as causes of hyperthyroidism 5, 6.
- Painless (silent) thyroiditis can cause an excessive passive release of thyroid hormones, leading to hyperthyroidism 5.
- Hyperthyroidism can also be caused by an endogenous or exogenous extrathyroidal source, leading to an excessive concentration of thyroid hormones in tissues 5.
Types of Hyperthyroidism
- Overt hyperthyroidism is defined as a low or undetectable thyrotropin (TSH) level with elevated triiodothyronine (T3) or thyroxine (T4) values 2, 6.
- Subclinical hyperthyroidism is defined as low or undetectable TSH with normal T3 and T4 levels 2, 6.
- Thyrotoxicosis is a condition characterized by the presence of excess thyroid hormones in the body, which can be caused by hyperthyroidism or other conditions 2, 3.