1. How to treat hyperthyroidism
There are three main treatments for hyperthyroidism, including internal antithyroid drug (ATD) treatment, nuclear medicine iodine-131 treatment, and surgical treatment. Internal ATD treatment is relatively mild, and the dosage can be adjusted in time during treatment. The disadvantage is the long duration of treatment, usually 1-2 years of standardized treatment; during treatment, ATD can cause allergy, damage to liver, kidney function and hematopoietic system and is often difficult to maintain once it occurs. Another disadvantage is that hyperthyroidism is prone to relapse when the drug is discontinued or reduced, and the relapse rate of ATD treatment has been reported to be around 40-60%.
Iodine-131 treatment is easy to use and usually only one dose of iodine-131 is given. The symptoms of hyperthyroidism start to improve about 4 weeks after treatment, and the remission rate of hyperthyroidism usually reaches 75-80% in about one year. Iodine-131 treatment does not cause allergy, damage to liver and kidney function or hematopoietic function. Those hyperthyroid patients with allergy, abnormal liver and kidney function or decreased blood cells due to ATD treatment can still be treated. Some patients with no significant improvement or incomplete remission of symptoms after six months of iodine-131 treatment can be retreated with iodine-131 again. Patients with hyperthyroidism with severe proptosis should prefer surgical treatment.
Surgery is usually used to treat hyperthyroidism by subtotal thyroidectomy, which is a rapid treatment to relieve hyperthyroidism, especially for patients with significantly enlarged thyroid gland with proptosis and hyperthyroidism with nodules, but it is traumatic and may cause complications such as damage to the laryngeal nerve and hypoparathyroidism in some cases. Some patients still have recurrence of hyperthyroidism after surgery.
At present, in the United States, iodine-131 therapy has become the preferred treatment for adult hyperthyroid patients, with about 80% or more of patients treated with iodine-131. In Europe, iodine-131 therapy for hyperthyroidism is also very important. In China, with the increased awareness of hyperthyroidism and comprehensive understanding of radioactive iodine treatment for hyperthyroidism, more and more doctors and patients are choosing iodine-131 treatment for hyperthyroidism.
2. Which type of hyperthyroidism is suitable for radioactive iodine-131 treatment?
It is suitable for all diagnosed hyperthyroid patients, especially for those who have the following conditions: abnormal liver function, hypocellularity unsuitable for antithyroid drug (ATD) treatment; allergy to ATD drugs; relapse after ATD treatment; relapse after surgery or unwillingness to operate.
Nodular goiter with hyperthyroidism; chronic lymphocytic thyroiditis (Hashimoto’s disease) with hyperthyroidism; simple goiter can also be treated with iodine-131 from a cosmetic point of view (in order to reduce the size of the thick neck).
3. What preparations should be made before iodine-131 treatment for hyperthyroidism?
Since iodine-containing foods, medications and antithyroid drugs can affect the uptake of iodine-131 by the thyroid gland, it is usually necessary to stop using antithyroid drugs and iodine-containing foods and medications for at least 4-6 weeks prior to treatment. Symptomatic treatment of hyperthyroidism symptoms such as panic attacks, low white blood cells and abnormal liver function should be continued during discontinuation of medication.
4. What tests should be done before iodine-131 treatment for hyperthyroidism?
Before taking iodine-131 treatment, patients with hyperthyroidism should have iodine-131 uptake rate measurement, biochemical indicators of thyroid function such as FT3, FT4 and TSH measurement, thyroid antibodies such as A-Tg, A-TPO and TSH receptor antibodies (TRAb, TBII, etc.) measurement, thyroid ECT or ultrasound examination to clarify the size of thyroid gland and preliminary determination of the nature of thyroid nodules. Blood tests, liver and kidney functions, etc.
5. What is iodine-131? What are its medical uses?
Iodine-131 is a radioactive drug, an isotope of iodine, which decays by half every 8 days (half-life of 8 days); the beta radiation it emits is used for therapeutic purposes. Iodine-131 accumulates only in the thyroid tissue and is not taken up by other tissues. The beta radiation emitted by iodine-131 has a range of only 1 mm in the thyroid gland, and the energy it releases can destroy the hyperfunctioning thyroid tissue and shrink the enlarged thyroid gland as if it had been operated on once, with minimal effect on the surrounding tissues.
6. Nuclear medicine examination of the thyroid is safe
The chemical amount of iodine-131 used in the determination of iodine absorption rate of thyroid gland is very small, and the chemical amount of radioactive dose commonly used is 1.6×10-11 grams for 2 microjuice, which has no effect or harm to human body.
The radioactive drug 99mTcO4-, which is commonly used for thyroid imaging, has a half-life of only 6 hours. The radioactive dose received by the patient is less than that of a single X-ray chest film. Iodine-131 can also be used for diagnostic imaging, but only in special cases such as looking for ectopic thyroid glands or looking for metastases of thyroid cancer.
7. Can hyperthyroidism treated with iodine-131 cause hypothyroidism?
The three current methods of hyperthyroidism treatment (anti-thyroid medication, iodine-131, and surgery) can cause hypothyroidism. As long as hyperthyroidism is cured and does not recur, a certain percentage of hypothyroidism occurs every year. Therefore the occurrence of hypothyroidism is not caused by iodine-131 treatment.
The incidence of hypothyroidism due to hyperthyroidism treated with iodine-131 varies from hospital to hospital at home and abroad, but in China it is mostly about 10%, and the trend is increasing year by year.
8. Iodine-131 can cure hyperthyroidism and you can still have children
After six months of iodine-131 treatment, you can get pregnant after the symptoms of hyperthyroidism are relieved and the biochemical indicators of thyroid function return to normal. Even if hypothyroidism occurs after hyperthyroidism treatment, those who have normal biochemical indicators of thyroid function through drug replacement therapy (commonly used as eugenol) can also get pregnant, and can continue to take eugenol during pregnancy and breastfeeding, but the dosage should be adjusted by the doctor ……
9. Not all patients with hyperthyroidism are suitable for Iodine-131 treatment
Iodine-131 therapy should not be used in patients who are pregnant and breastfeeding and in patients in the acute phase of acute myocardial infarction.
People with severe renal impairment should also not be treated with iodine-131, this is because all iodine-131 is excreted in the body from the urine except for the uptake of iodine-131 by the thyroid gland. If the kidney function is poor, iodine-131 cannot be eliminated in the body in time and iodine-131 accumulates in the body, especially in the kidney for a long time exposing the patient to unnecessary exposure. Iodine-131 treatment can be used after the renal function is in remission.
10. Can anti-thyroid medication and iodine-131 therapy be taken together in hyperthyroid patients?
Since antithyroid medication can affect the uptake of iodine-131 by the thyroid gland and the biochemical measurements of thyroid function, the patient should generally stop taking antithyroid medication (ATD) and abstain from iodine-containing food and medication for more than 2-4 weeks before undergoing the relevant nuclear medicine examination and treatment. However, in severe hyperthyroidism, because of the patient’s poor general condition, in order to prevent the aggravation of the disease or the emergence of hyperthyroid crisis, the drug is usually stopped only three days before the determination of the iodine uptake rate of the thyroid gland, and the ATD treatment is continued for 2-4 weeks after taking iodine-131 for three days, after which the dosage is reduced or stopped under the guidance of the doctor.
11. Can proptosis disappear after Iodine-131 treatment?
There are three types of hyperthyroidism with proptosis: some appear before the onset of hyperthyroidism, some appear during the treatment of hyperthyroidism, and a few patients may appear after the control of hyperthyroidism or even when they have hypothyroidism. There is no specific treatment for hyperthyroidism with proptosis. In general, most of the hyperthyroidism proptosis is reduced after Iodine-131 treatment, but in very few patients, the proptosis is still aggravated after the hyperthyroidism symptoms are controlled.
12. What should I do if I have low thyroid?
Once hypothyroidism is diagnosed, the treatment is relatively simple. Thyroid hormone replacement therapy (eugenol) is used to bring the patient’s thyroid hormone levels to normal. As this treatment only replenishes the insufficient thyroid hormone in the patient’s body, it will not cause any damage to the patient’s liver, kidney function or hematopoietic system, nor will it affect pregnancy or breastfeeding, as long as the thyroid hormone level in the body is adjusted to the normal range. It is just like buying food to eat when you cannot grow your own food.