1. How to treat hyperthyroidism?
There are three main treatments for hyperthyroidism, including internal antithyroid drug (ATD) therapy, iodine-131 therapy in nuclear medicine, and surgical treatment.
Internal ATD treatment is relatively mild and the dosage can be adjusted in time during the 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 in symptoms or incomplete remission after six months of iodine-131 treatment can be retreated with iodine-131 again. The disadvantage of iodine-131 treatment is that it is slow to relieve symptoms. Surgical treatment should be preferred for patients with hyperthyroidism with severe proptosis.
Surgical treatment is usually performed by subtotal thyroidectomy for hyperthyroidism, which provides rapid relief of hyperthyroidism, especially for patients with markedly enlarged thyroid glands with proptosis and hyperthyroidism with nodules, but it is traumatic and may cause surgical complications such as damage to the recurrent laryngeal nerve and hypoparathyroidism in some cases. Some patients still have recurrence of hyperthyroidism after surgery.
Generally, the chance of occurrence or hypothyroidism after iodine-131 treatment and surgery is higher than that of drug treatment.
2. Which type of hyperthyroidism is suitable for radioactive iodine-131 treatment?
Toxic diffuse goiter, especially hyperthyroidism that occurs in patients with the following conditions can be treated with iodine-131: abnormal liver function, hypocellularity unsuitable for antithyroid drug (ATD) treatment; allergy to ATD drugs; relapse after ATD treatment; relapse after surgical treatment or unwillingness to undergo surgery.
Toxic nodular goiter with hyperthyroidism; chronic lymphocytic thyroiditis with hyperthyroidism; non-toxic goiter can also be treated with iodine-131 from cosmetic point of view.
3.What preparations should be made before iodine-131 treatment for hyperthyroidism?
Because iodine-containing foods, medications and antithyroid drugs can affect the uptake of iodine-131 by the thyroid gland, antithyroid drugs and iodine-containing foods and medications should be stopped for at least 4-6 weeks before 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 their thyroid iodine-131 uptake rate measured, biochemical indicators of thyroid function such as TT3, TT4, FT3, FT4 and TSH measured, thyroid antibodies such as A-Tg, A-TPO and TSH receptor antibodies (TRAb, TBII, etc.) measured, thyroid nuclear imaging or ultrasound examination to clarify the size of the thyroid gland and make preliminary judgments. The nature of the thyroid nodule, blood count, liver and kidney function, 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); it emits gamma rays for imaging and beta rays for treatment to perform diagnostic and therapeutic functions. Iodine-131 accumulates only in the thyroid tissue and is not taken up by other tissues. The beta rays emitted by iodine-131 have a range of only 2 mm in the thyroid tissue, 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 impact on the surrounding tissues.
Iodine-131 is mainly used for the treatment of hyperthyroidism and Plummer’s disease. It is also used for thyroid function measurement, thyroid imaging, and the treatment and follow-up of well-differentiated thyroid cancer and its metastases.
6. 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 10-25%, and the trend is increasing year by year.
7.Iodine-131 can cure hyperthyroidism and you can still have children
After one year of iodine-131 treatment, hyperthyroidism symptoms are relieved and biochemical indicators of thyroid function return to normal, then you can get pregnant. Even if hypothyroidism occurs after hyperthyroidism treatment, those with normal biochemical indicators of thyroid function after drug replacement therapy can also get pregnant.
8. Not all patients with hyperthyroidism are suitable for iodine-131 treatment.
Patients who are pregnant, breastfeeding or in the acute stage of acute myocardial infarction cannot be treated with iodine-131; those with severe renal impairment cannot be treated with iodine-131 either, because all iodine-131 is excreted in 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.
If the thyroid gland is extremely enlarged or the thyroid gland behind the sternum is swollen with symptoms of compression, iodine-131 treatment is prohibited or used with caution because the oversized thyroid gland will aggravate the symptoms of compression due to mild inflammation during iodine-131 treatment, resulting in breathing difficulties.
9. Can anti-thyroid medication and iodine-131 therapy be used together in hyperthyroid patients?
Since antithyroid medication can affect the uptake of iodine-131 by the thyroid gland and the results of biochemical measurements of thyroid function, the patient should generally stop taking antithyroid medication (ATD) and refrain from iodine-containing food and medication for more than 4 weeks before undergoing nuclear medicine examination and treatment. However, in patients with severe hyperthyroidism, because of the patient’s poor general condition and the slow therapeutic effect of iodine-131, in order to prevent the aggravation of the disease or the emergence of hyperthyroidism crisis, the drug is usually stopped only three days before the determination of the iodine absorption rate of the thyroid gland, and ATD treatment is continued after three days of iodine-131 until iodine-131 takes effect.
10. Can I get rid of proptosis after Iodine-131 treatment?
Hyperthyroidism with proptosis may appear before the onset of hyperthyroidism, or during the treatment of hyperthyroidism, or in some patients, after the control of hyperthyroidism or even during 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.
11.What should I do if I have low thyroid?
Once hypothyroidism is diagnosed, the treatment is relatively simple. Thyroid hormone replacement therapy 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 damage to the patient’s liver and kidney function and hematopoietic system, nor will it affect pregnancy and 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. However, when heart disease is accompanied by low thyroid, supplemental treatment should be started from small doses.
12.Iodine-131 can also treat thyroid cancer
The thyroid gland is an endocrine organ in the body, which can produce thyroid hormones, and iodine is one of the substances used to synthesize thyroid hormones. Iodine-131 is an isotope of iodine, which has the same chemical properties as iodine, and can be selectively taken up by the thyroid gland after oral administration. Some functional thyroid cancers also have iodine uptake. These thyroid cancer cells are able to take up iodine after normal thyroid tissue has been expelled. Unlike ordinary iodine, iodine-131 emits rays that can effectively destroy tumor cells.
13.Thyroid cancer patients also need iodine-131 treatment after surgery
During the surgery, physicians only judge whether the removal is clean according to the naked eye, or there will be a little residue in order to protect the surrounding normal tissues. At this time, applying iodine-131, no matter where the cancer cells are, if it has the function of iodine uptake, iodine-131 will gather there to destroy the tumor cells. Therefore, it is necessary to apply iodine-131 treatment after surgery to reduce the possibility of local recurrence and prolong the survival period. And for metastatic lesions in other sites, as long as they have iodine uptake function, they can also be treated with iodine-131.
14.Iodine-131 treatment for thyroid cancer also has side effects
Due to the high dose of iodine-131 treatment, dry mouth, swelling and pain in salivary gland area, swelling in front of the neck, pain in thyroid area and some digestive symptoms may occur in the early stage after the treatment, as well as a transient decrease in white blood cells and platelets, which can be relieved by symptomatic treatment by physicians. It is best to consider pregnancy only after one year of iodine-131 treatment.
15.What should patients do to prepare for thyroid cancer before iodine-131 treatment?
Patients should stop taking thyroid tablets and T3 tablets and all iodine-containing drugs for 4-6 weeks before applying iodine-131 treatment under the guidance of physicians.
16.What do I need to pay attention to after iodine-131 treatment for thyroid cancer?
Due to the high dose of iodine-131 used for treatment, patients should stay in isolation ward for the first 3-5 days after taking the drug, and can be discharged after 3-5 days, but should not go to public places and try to avoid contact with pregnant women and children. After 3-6 months of iodine-131 treatment, the doctor can decide whether to repeat the treatment or choose other treatments according to the specific situation.
17.There are requirements for iodine-131 treatment for thyroid cancer patients after surgery
Iodine-131 therapy is not suitable for pregnant and lactating women, patients with laboratory tests showing WBC <3.0×109/L, PLT <90×109/L, severe liver and kidney dysfunction, and patients whose postoperative neck wound has not completely healed.