What is Radioactive Iodine (Atom) Therapy?

Radioactive iodine therapy is a radiation-based treatment method used in the treatment of differentiated thyroid cancers and some types of hyperthyroidism and popularly called ‘atom therapy’. The thyroid gland uses iodine in the synthesis of thyroid hormones, which is its main function for our body. Many foods, especially iodized table salt, are natural sources of iodine. An important part of the iodine taken into our body is retained and stored by the thyroid gland. This unique relationship between iodine and the thyroid gland allows the radioactive form of iodine, Iodine-131, to be used for therapeutic purposes in some diseases. Some well-differentiated tumors of the thyroid gland (papillary carcinoma, follicular carcinoma) consist of cells that mimic normal thyroid tissue and have very similar structural features. Due to these features, they capture iodine and take it into the cell, although not as much as normal cells. However, they do not have the ability to distinguish between radioactive and non-radioactive iodine. If the body is not saturated with non-radioactive iodine, the radioactive iodine used for treatment is retained by the cells of the normal thyroid cells, thyroid cancer or lymph node-organ spreads left behind after the operation. The purpose of the iodine-restricted diet applied before the treatment is to starve the body for non-radioactive iodine and to ensure that the radioactive iodine reaches the desired targets in high amounts. Thus, the iodine-131 (atom) taken into the cell destroys the cell with the effect of beta radiation. This is one of the oldest molecular-targeting (intelligent) treatment methods.

Radioactive iodine therapy; It is performed to prevent recurrence of the disease by leaving no normal or cancerous thyroid cells after the operation in thyroid cancer, and to provide treatment if there is lymph node or organ spread. Very low doses of radioactive iodine are used for imaging purposes (whole body Iodine-131 scanning scintigraphy) to monitor whether residual tissues are destroyed after treatment.

In patients diagnosed with thyroid cancer, whose tumor diameter is below a certain size and who do not have high-risk pathological criteria, follow-up is possible by keeping the thyroid drug dose at the required level without radioactive iodine treatment, if residual tissue and metastasis (spread) are not detected by post-operative examinations.

Radioactive iodine treatment can be applied to patients of all age groups. During pregnancy, no radioactive material can be used for treatment or examination purposes. Our female patients who received treatment should not have children for 1 year, and our male patients for 6 months.


An iodine-restricted diet is applied for at least 15 days before radioactive iodine treatment. Radioactive iodine antibiotics etc. It is in capsule form, similar to the drugs we use in daily life. It is applied by drinking with a protected pipette. Afterwards, it is necessary to stay in specially insulated rooms until the radiation emitted from the body and excreted with urine and faeces for 1-3 days, depending on the dose given, reaches a level that will not harm the health of the individuals around. Our patients leaving the hospital should not come into contact with pregnant and children under the age of 18 for 2-3 weeks, should not spend time with adults at close distance (less than 1 meter) and for a long time, should not enter crowded areas, use public transportation as much as possible. They must stay in a separate room at home. Short-term (about 30 minutes) encounters with individuals (except pregnant and children) at a distance of 1 meter do not carry any risk. For breastfeeding mothers; Since radioactive iodine passes into breast milk, breastfeeding should be terminated. It is important for the protection of other individuals in the house to use a separate sink – bathroom – toilet, if possible, and to wash hands and surfaces carefully with plenty of water for 15 days after the treatment. Soap, toothbrush, towel, cutlery, etc. Care should be taken not to use personal materials by anyone else. The clothes used in the treatment room should be ventilated for 1 week and washed with plenty of water separately from other laundry, and it is appropriate to wash the sheets, towels and clothes separately for 15 days after the treatment.


Although post-treatment side effects are related to the dose of radioiodine taken, they are usually mild and transient. In the presence of residual thyroid tissue, tenderness in the neck and pain during swallowing may be felt. Mild nausea, fatigue, and increased need for sleep are common side effects in the first days. Since radioactive iodine is also involved in the salivary glands, a decrease in the sense of taste or a change in taste (metallic taste, etc.) can be observed in the early period, swelling in the salivary glands, pain and dry mouth in the late period. In the first week of treatment, rinsing the mouth with lemon juice, drinking plenty of water, chewing gum and applying ice to the salivary glands can reduce the level of these side effects. However, there is no definitive data on this subject. It is important to drink plenty of water and urinate after the first 24 hours in order to reduce the radiation dose that the body will receive and accelerate its removal from the body. Temporary absence of menstruation may be possible due to the radiation exposure of the internal genital organs and the lack of thyroid hormones in women. Drinking plenty of water and not keeping the urine waiting is effective in reducing this effect.

I wish you healthy days.

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