Treatment of Hyperthyroidism I

The most commonly used treatment in Korea is medication therapy, and most doctors prefer oral medication as the first option. Drug treatment using antithyroid agents lowers thyroid hormone levels by preventing the thyroid from producing or secreting thyroid hormones. Radioactive iodine administration and surgery are treatments that destroy or remove thyroid tissue.

1. Drug treatment (antithyroid medication) The medications currently used to treat hyperthyroidism are divided into two types: thionamide drugs, which include methimazole or carbimazole, and propylthiouracil.

① Selection of antithyroid medication For hyperthyroidism, methimazole is used as the first-line treatment. Methimazole or carbimazole is usually taken once a day, while PTU (propylthiouracil) is taken in 2-3 divided doses per day.

② Treatment effect and duration Antithyroid medication begins to improve symptoms only about 2-3 weeks after treatment starts, and thyroid function is normalized in most cases after 6-8 weeks. In the early stage of treatment, thyroid hormone levels are assessed through blood tests every 4-6 weeks, and once thyroid function has normalized, blood tests are performed at 2-3 month intervals.

③ Treatment response and recurrence After drug treatment, 40-50% of patients are cured, but about 50% will relapse 1-2 years later even after stopping the medication. Recurrence after treatment usually appears within 1 year, but in rare cases it may recur after 5 years. Therefore, even after stopping drug treatment, thyroid function should be checked periodically through blood tests.

④ Side effects Side effects usually occur early in treatment, within 1-2 months after starting the medication. Hives, skin rash, and itching are common symptoms, and some patients may also experience joint pain, hair loss, and fever. In such cases, symptoms can be easily controlled by stopping the medication or using antihistamines. A temporary decrease in white blood cells may also be seen on blood tests, but if it does not progress to agranulocytosis, there is no need to stop the medication or provide special treatment.

2. Radioactive iodine treatment Radioactive iodine treatment is a method in which radioactive iodine, taken into the body by drinking water containing iodine that emits radiation, destroys the thyroid so that it can no longer produce thyroid hormones.

① Indications It is especially useful when the thyroid is relatively large and symptoms are severe, when there are side effects from antithyroid medication or the patient does not want to take medication, and when hyperthyroidism recurs after surgery.

② Treatment effect After radioactive iodine is administered, there is usually no noticeable change in symptoms within the first month, and in rare cases symptoms may actually worsen. Symptoms begin to improve around 2-4 weeks after administration, and the maximum effect appears after 2 months.

③ Side effects A side effect that may occur after radioactive iodine administration is hypothyroidism. It is difficult to predict whether hypothyroidism will develop after treatment, but it occurs in about half of patients. In such cases, thyroid function does not recover, so thyroid hormone must be taken for life. However, unlike treatment for hyperthyroidism, hypothyroidism causes almost no suffering during treatment, the cost of treatment is very low, and if thyroid hormone is taken, the difference from a healthy person is almost negligible. For this reason, radioactive iodine treatment is sometimes performed with the expectation that thyroid hormone will need to be taken.

④ Precautions Before radioactive iodine treatment, foods high in iodine, such as seaweed (miyeok, gim, dasima), or iodine-containing products (multivitamins containing iodine, mouthwash containing large amounts of iodine, vaginal wash products) should be avoided for at least 2 weeks. This is because the effectiveness of radioactive iodine treatment decreases when iodine intake is high.

So far, I have explained Treatment of Hyperthyroidism I. In the next part, we will look at Treatment of Hyperthyroidism II.

Source: Korea Disease Control and Prevention Agency National Health Information Portal