Many people know that atomic bomb and hydrogen bomb are a kind of nuclear weapon with great lethality, which is the application of radionuclide and nuclear technology in military, but they do not know much about the application of nuclear technology in medicine. In recent years, with the development of science and technology and the improvement of people’s cultural quality, the awareness of radionuclide treatment work has gradually increased, but it is not deep and comprehensive. For example, radioactive iodine treatment for hyperthyroidism is an effective treatment method, which is simple, safe, with high one-time cure rate, low recurrence rate and low cost, so it is welcomed by patients. However, there are still many patients who do not understand this method or have insufficient and one-sided knowledge about it. As nuclear medicine practitioners, we have the responsibility to help people understand and appreciate the knowledge about nuclear medicine treatment. Here I will discuss some basic knowledge about radioactive iodine treatment for hyperthyroidism for reference only. Hyperthyroidism (abbreviated as hyperthyroidism) is a very common endocrine disorder, which is a combination of increased metabolic rate due to excessive secretion of thyroid hormones. There are many causes. The pathology is diffuse, nodular or mixed goiter and a variety of organ and tissue lesions caused by hyperthyroidism, including a series of pathophysiological changes that occur due to excessive thyroid hormones acting on various organs throughout the body. There are many types of hyperthyroidism, but the common feature is excessive thyroid hormones, so we will not go into details.
Some patients with hyperthyroidism may experience some conscious symptoms, such as panic, rapid heartbeat, fear of heat, excessive sweating, irritability, fatigue, loss of weight, increased appetite, increased stool, etc. Some patients may also find that their neck is thickened and their eyes protrude. If the above symptoms and signs appear, it is likely that the patient is suffering from hyperthyroidism and should go to the hospital for relevant examinations in time to make a clear diagnosis. In hospitals, doctors usually arrange to do serum T3 and T4 (including TT3, FT3 and FT4) according to the patient’s symptoms.
The doctor will also do a thyroid scan to understand the shape, location, size, presence of nodules and function of the thyroid gland. If it is found that the T3 and T4 levels are increased (some people only have one item increased), the TSH level is decreased and the thyroid gland is diffusely enlarged or has toxic thyroid adenoma. The diagnosis of hyperthyroidism is basically confirmed. If serum T3 and T4 levels are not significantly increased, further iodine uptake rate of the thyroid gland and thyroxine suppression test and thyroid hormone releasing hormone (TRH) excitation test can be done. These tests are helpful in the diagnosis of atypical hyperthyroidism.
Patients suffering from hyperthyroidism need not be alarmed, as the disease is completely curable with the advancement of medical science today. However, unlike a cold or flu, it will not be cured in a few days and there is a process. As long as you listen to the doctor’s advice and take regular medication, it is not difficult to cure. At present, there are four kinds of treatment methods in common use: internal anti-hyperthyroidism medication, surgery, radioactive iodine treatment and traditional Chinese medicine.
Internal treatment refers to the use of anti-thyroid drugs, such as tabazol, hyperthyroidism, methylthioxypyrimethamine, propylthioxypyrimethamine, etc., which mainly play the role of inhibiting the synthesis of thyroid hormones. This is a commonly used method with positive efficacy and easy method. The disadvantage of this method is the long treatment time, at least one year of regular medication, and the high relapse rate (up to 50%) after stopping medication.
Surgery is also a treatment method for hyperthyroidism, especially for toxic thyroid adenomas. If the adenoma is removed cleanly, there is usually no recurrence of hyperthyroidism in the future. However, after all, it is a surgical procedure with certain risks and a high recurrence rate (30%), and there is also a risk of hypothyroidism, especially in diffuse enlarged hyperthyroidism.
According to the theory of Chinese medicine, hyperthyroidism is considered to be caused by internal injuries and the seven emotions of the heart and liver with yin deficiency and fire, and dialectical treatment is also effective, but the course of this disease is long and long-term decoction of Chinese medicine is not very practical, and some results are also poor.
The use of radioactive iodine treatment is currently recognized as an effective method in the world. Former U.S. President George W. Bush, who suffered from hyperthyroidism during his administration, was finally treated with radioactive treatment after consultation and discussion by many world-class authoritative medical experts, and received good treatment results. This is now included as the preferred method in some Western countries. Why is isotope therapy so effective? Because iodine is a necessary raw material for the synthesis of thyroid hormones in the thyroid gland, and radioactive iodine and stable iodine have the same physiological and biochemical properties, so the thyroid tissue also has a high absorption and concentration capacity for radioactive iodine. In general, the concentration of iodine in the thyroid gland can reach 25 times of the plasma concentration. In patients with hyperthyroidism, the rate and amount of synthesis of thyroid hormones increase, so the concentration of radioactive iodine is even higher, up to 80-90%. The effective half-life of iodine in the thyroid gland is 3.5 to 4.5 days on average. The large amount of concentrated radioactive iodine exposes the thyroid gland to radiation, and some of the thyroid tissue is destroyed, resulting in a decrease in thyroid hormone production and remission or cure of hyperthyroidism. Iodine-131 is an unstable radioactive radionuclide that emits γ and β rays during the decay process, with β rays accounting for 99% of the therapeutic effect. Because beta rays have a short range of 1 mm on average and 2.2 mm on the longest, they can destroy thyroid tissues, but have little or no effect on the surrounding tissues and organs. This shows that radioactive iodine is a safe and easy way to treat hyperthyroidism.
Which patients with hyperthyroidism are suitable for radioactive iodine therapy? It is generally accepted that iodine-131 therapy is suitable for both male and female adult patients. It is the treatment of adolescents and children that is being debated. A long time ago, there were concerns about the risk of cancer, leukemia, and congenital abnormalities in the fetus with iodine-131.
After half a century of clinical practice these fears have been eliminated. Statistics of more than 1 million patients at home and abroad show no increase in the incidence of leukemia and thyroid malignancies, no more than natural incidence of fetal malformations, and no effect on fertility and offspring development. These have been extensively reported in the literature. The current expert consensus is that hyperthyroidism during pregnancy and lactation should not be treated with iodine-131 because it can cause hypothyroidism in the fetus or infant.
Therefore, we believe that iodine-131 is a safe form of treatment for patients of all ages (including women of childbearing age and children), except for pregnant and lactating women, and can be the treatment of choice for adults.
Treatment of hyperthyroidism with radioactive iodine is usually performed in the nuclear medicine department. The nuclear medicine doctor decides the time and dosage of radioactive iodine based on a comprehensive analysis of the patient’s hyperthyroidism symptoms, clinical manifestations, laboratory test results, thyroid gland iodine absorption function and thyroid scan results. Generally speaking, after the diagnosis of hyperthyroidism is confirmed, some preparatory work should be done before treatment with iodine-131, such as controlling certain heavier complications and abstaining from iodine-containing foods or medications. Before and after taking iodine-131, some auxiliary therapeutic agents should be dispensed according to the clinical manifestations, and certain reactions should be noted some time after taking the drug. Most of the patients can be controlled after treatment, and a cure can be achieved with a single dose of the drug. A small number of patients require a second treatment. After taking Iodine-131, it takes more than 3 weeks to start to show the effect of treatment.
Within 3 months, the symptoms will gradually improve, the thyroid gland will shrink, and the proptosis will be reduced in some patients. For those who need a second treatment, it should be done after six months.
Some patients with hyperthyroidism have protruding eyes, which is called proptosis. The causes are complex and may be related to certain immune disorders in the body, and some people have found that there is a substance in the serum of these patients that is related to the occurrence of proptosis. The occurrence and aggravation of proptosis are not parallel to the condition of hyperthyroidism. Most patients with hyperthyroidism will not have their proptosis aggravated by iodine-131 treatment, but only a few cases may have their proptosis aggravated. This should be properly understood.
Hyperthyroid patients generally do not have any reaction after taking iodine-131, and only a few patients experience some side effects.
Some reactions that occur within 2 weeks after taking the drug are called early reactions, mainly nausea, vomiting, dizziness, weakness, and in a few patients, rash and itching, which are generally mild and can disappear on their own. Some patients may experience transient exacerbation of hyperthyroidism, which is usually temporary, and very few patients with severe symptoms have to be hospitalized for observation. The main complication in the late stage is hypothyroidism (also known as hypothyroidism). It is caused by insufficient synthesis and secretion or physiological effect of thyroid hormones. One type of hypothyroidism caused by iodine-131 treatment is transient hypothyroidism, which is mild and can disappear on its own after 6 to 9 months, because of the recovery of incomplete thyroid cells damaged by radiation or compensatory proliferation of residual tissues. The other is permanent hypothyroidism, the incidence of which is reported to be 2-5% in the first year, and increases by 2-3% year by year as time goes on. Low thyroid is not terrible, as long as the right amount of thyroxine is supplemented, you can maintain normal thyroid function. Some scholars believe that hypothyroidism is a natural history of hyperthyroidism, which can occur after various treatments and is not unique to iodine-131 treatment.
In summary, several methods of treating hyperthyroidism have their own characteristics, and it is necessary to develop the correct treatment plan for the individual patient. In contrast, radioactive iodine-131 treatment for hyperthyroidism is widely applicable, simple, safe and effective, with few doses, few complications, high cure rate and low cost, and can be the first choice for most patients.
Recently, many people have raised some specific questions about radioactive iodine-131 treatment for hyperthyroidism, and the answers are as follows.
1. Radioactive iodine treatment for hyperthyroidism is usually performed in the outpatient department of nuclear medicine and does not require hospitalization.
2. The administration of radioactive iodine must be done under the guidance of a nuclear medicine physician, and the medication must not be taken away and cannot be mailed.
3. Before and after receiving radioactive iodine treatment, it is recommended to eat light and nutritious food, and to eat less seafood and iodine-containing food.
4. Young women with hyperthyroidism who have received radioactive iodine treatment can generally become pregnant six months after healing.
5. Young women with a history of hyperthyroidism who have improved after treatment and are asymptomatic and have normal laboratory tests do not need to take radioactive iodine.
6. Giant goiters without hyperthyroidism can also receive radioactive iodine therapy.