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How does iodine-131 treat hyperthyroidism?

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linear accelerator; external beam radiation therapy — radiation therapy External beam radiation therapy (also known as external beam teletherapy, or long-distance therapy) being delivered using a machine known as a linear accelerator.

Iodine-131 is used to treat hyperthyroidism by leveraging the thyroid gland's natural biological process of absorbing iodine.

When ingested, the radioactive iodine-131 is taken up by thyroid cells in the same manner as nonradioactive iodine. Once concentrated within the gland, the emitted radiation destroys a portion of the glandular tissue. This process effectively reduces the size of the thyroid and decreases its production of thyroid hormone, thereby bringing the gland's function back to a normal level.12

While this treatment is highly effective for conditions such as Graves disease and nodular goitre, it is a significant medical intervention. It often results in hypothyroidism in most patients, requiring long-term management, and presents challenges in calculating the precise dosage needed to achieve the desired therapeutic effect.12