Radioiodine therapy is a form of internal radiation therapy using radioactive iodine. Radioiodine therapy is used to treat certain thyroid conditions and iodine-accumulating thyroid cancer. The medication is taken orally, after which you will remain in hospital for a few days.
The treatment targets cells that take up iodine. Temporary side effects may occur. Pregnancy and breastfeeding preclude this treatment.
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What is radioiodine therapy and who is it suitable for?
Radioiodine therapy utilises the thyroid’s natural ability to absorb iodine. After ingestion, the radioactive substance enters the thyroid tissue. Its radiation causes damage to the thyroid cells that absorb it, thereby selectively destroying overactive tissue. The term ‘radioiodine therapy’ refers to the same procedure.
Radioiodine therapy is used to treat selected thyroid conditions. In cases of hyperthyroidism, hormone production is usually first suppressed with medication. Depending on the cause, this is followed by long-term treatment.
Radioiodine therapy may be considered for the following benign conditions:
- Graves’ disease: Drug treatment alone is insufficient.
- Thyroid autonomy: Cells produce too many thyroid hormones independently of normal regulation. This includes disseminated autonomy, in which areas of cells distributed throughout the organ function autonomously.
- Hormone-producing nodules: Benign nodules cause hyperthyroidism.
- Nodular goitre: In this form of nodular thyroid enlargement, multiple nodules lead to hyperthyroidism.
Cold nodules are not classified as hormone-producing nodules. If cancer is suspected, surgery is generally the preferred option. Whether radioiodine therapy is an alternative to surgery depends on the diagnosis and the treatment objective.
Women who are pregnant or breastfeeding must not be treated with radioiodine. Pregnancy must therefore be ruled out before treatment.
When is radioiodine used for thyroid cancer?
In certain differentiated forms of thyroid cancer, radioiodine therapy follows surgery. In papillary and follicular thyroid carcinomas, the tumours can store iodine. The treatment is intended to eliminate any remaining tumour tissue and prevent a local recurrence.
Additional radioiodine therapy may also be considered in cases of recurrent cancer or metastases. This is conditional on the carcinomas continuing to take up iodine.
Medullary and anaplastic thyroid cancers, on the other hand, do not respond to this treatment. These tumour types do not store iodine, meaning that the radiation dose cannot specifically target the malignant tissue.
How does the treatment affect the thyroid gland?
In the case of benign thyroid conditions, the effect usually takes some time to become apparent. It usually becomes evident after about two to three months. However, it may begin earlier or only become apparent within half a year.
If the thyroid gland has enlarged due to nodules, the organ may shrink by up to 50 per cent within a year. The extent of the reduction in thyroid size is compared with its size prior to treatment.
If hyperthyroidism persists six months later and relevant thyroid tissue is present, the guideline recommends planning a second course of radioiodine therapy.
The choice of suitable alternative depends on the condition being treated and the treatment objective.
| Procedure | Who is it suitable for? | Timeframe | Advantages and disadvantages |
|---|---|---|---|
| Radioiodine therapy | Selected benign conditions and iodine-accumulating cancers | Effect on benign conditions usually seen after around two to three months | Targeted uptake by thyroid cells; requires hospitalisation and has a delayed effect |
| Medication | Usually used as the initial treatment for hyperthyroidism | Before deciding on long-term treatment | Initially inhibits hormone production; may be insufficiently effective in conditions such as Graves’ disease |
| Thyroid surgery | Tends to be used where cancer is suspected or where there is pressure on neighbouring organs | Surgical intervention | May be more appropriate in these situations; requires an operation |
How do you prepare for radioiodine therapy?
Before treatment, a radioiodine test helps to calculate the appropriate dose.
The following points are relevant for preparation:
- Low-iodine diet: For benign conditions, the guidelines recommend a diet free from additional iodised salt and sea fish for two weeks.
- Contrast agents: Before radioiodine therapy for a benign thyroid condition, a gap of at least two months should be observed, where possible, following the use of iodine-containing X-ray contrast agents.
- Pregnancy: This must be ruled out before radioiodine therapy.
- Personal belongings: Please check in advance what you are permitted to bring with you to the nuclear medicine ward.
Some items may not be taken home immediately after the radioiodine therapy has been carried out. You will be informed of the relevant regulations before you are admitted to the hospital.
How is radioiodine therapy carried out?
The preparation is swallowed in solid form or administered dissolved in water. For reasons of radiation protection, radioiodine therapy in Germany is carried out on an inpatient basis.
The typical procedure involves the following steps:
- Treatment begins with the administration of the calculated dose, either as a capsule or as a liquid.
- You will stay in the shielded treatment ward for a few days.
- Visitors are generally not permitted during your hospital stay.
- Before discharge, the staff will measure how much radiation is still being emitted by your body.
- You may leave the ward as soon as the radioactivity falls below the prescribed limit.
In the first 24 hours after administration, you should drink plenty of fluids and empty your bladder regularly. This helps to reduce the radiation exposure to your bladder.
What are the risks?
Possible side effects include temporary discomfort in the throat and head area. These include swelling of the throat, a sore throat, dry eyes and changes in taste.
In Graves’ disease, eye problems may develop or worsen. The guideline states that around 5 per cent of patients require glucocorticoids, and up to around 15 per cent may require them if additional risk factors are present. Eye symptoms can also occur independently of radioiodine therapy.
Serious complications, such as heart problems, are very rare. In the treatment of thyroid cancer, damage to the salivary glands can cause a dry mouth.
Following radioiodine therapy for thyroid cancer, there is a slightly increased risk of developing a second cancer later on.
What should you bear in mind after treatment?
After discharge, it may be advisable to avoid close physical contact with children, pregnant women and breastfeeding women for a few more days. The exact duration depends on your individual circumstances.
Both women and men should use contraception for at least six months following radioiodine therapy for benign thyroid nodules.
As part of follow-up care, thyroid function and the gland itself are monitored regularly. This allows doctors to assess whether the treatment has been sufficiently effective or whether further therapy is necessary.
What does health insurance cover?
Statutory health insurance covers inpatient radioiodine therapy if it is medically necessary and adequate.
Those with statutory health insurance pay 10 euros per calendar day for a hospital stay, limited to 28 days per calendar year. This co-payment is not the out-of-pocket cost for radioiodine therapy.
For private health insurance, reimbursement depends on the specific insurance policy.
Who carries out radioiodine therapy?
The treatment falls within the field of nuclear medicine. A doctor with specialist expertise in therapy involving open radioactive substances must decide whether it is justified.
A nuclear medicine clinic can calculate the required amount of iodine, organise the hospital stay and measure any residual radiation before discharge. The planned follow-up checks should also be finalised before treatment begins.
The following questions, amongst others, are suitable for the initial consultation:
- Why is radioiodine therapy an option for me?
- How is the required amount of iodine calculated?
- What personal belongings am I allowed to bring with me?
- What follow-up checks are planned?
You can find specialists in radioiodine therapy at the end of this text.
Frequently asked questions about radioiodine therapy
Is radioiodine therapy a form of radiotherapy?
Yes, it involves internal irradiation with radioactive iodine. The substance is taken up by the thyroid gland and acts primarily in the iodine-storing tissue.
How long do you stay in hospital for radioiodine therapy?
In Germany, patients are admitted to hospital for a few days. They can be discharged as soon as the radiation emitted by their body falls below a specified limit.
When can an effect be expected?
In the case of benign conditions, the effects usually begin after about two to three months. They may start sooner or take up to half a year.
How do you feel after radioiodine therapy?
Temporary swelling of the neck, a sore throat, dry eyes or a change in taste may occur. Following treatment for thyroid cancer, damage to the salivary glands may also cause a dry mouth.
Can radioiodine therapy be repeated?
Yes, further treatment may be considered in cases of iodine-retaining, recurrent thyroid cancer or metastases. If benign hyperthyroidism persists after six months and relevant tissue is still present, the guidelines recommend planning a second course of treatment.
When is surgery the more appropriate option?
Surgery is generally the preferred option if cancer is suspected or if symptoms arise due to pressure on neighbouring organs. Medullary and anaplastic thyroid carcinomas cannot be treated with radioiodine because they do not take up iodine.
