Is radioactive iodine treatment safe?

Radioiodine therapy

What is radioiodine therapy?

Radioiodine therapy is a nuclear medicine therapy that has been established worldwide and has been carried out since the middle of the last century for the treatment of thyroid dysfunction worthy of treatment, for example on the basis of thyroid autonomy or an autoimmune thyroid disease of the Graves disease type.

In addition, it is an integral part of therapy and aftercare for certain forms of thyroid cancer. Radioiodine therapy is also suitable for reducing the size of the thyroid gland in the event of an enlarged thyroid gland (so-called goiter) or if an operative procedure is associated with an increased risk of anesthesia or surgery due to concomitant diseases.

The radioactive iodine isotope iodine-131 with a half-life of approx. 8 days is used therapeutically. The predominant beta radiation and the fact that iodine (also the radioactive iodine-131) in the human body is mainly stored in the thyroid cells (so-called thyrocytes) are used therapeutically.

In Germany, there are special statutory provisions in the Radiation Protection Ordinance (StrlSchV) and in the “Radiation Protection in Medicine” directive with regard to the implementation of radioiodine therapy for the handling of radioactive substances used for diagnostic / therapeutic purposes. These regulations also regulate isolation for at least 48 hours after taking a radioiodine therapy capsule in special rooms on our therapy ward.

The inpatient stay - approx. 3 - 7 days (rarely longer) - depends on the level of activity of the therapy capsule, the storage in the thyroid or residual thyroid tissue, the natural physical decay and the excretion of the absorbed amount of activity by the body. Activities of 400 - 3000 MBq, rarely 6000 MBq (= Mega Bequerel, physical unit of radioactive activity) iodine-131 are administered.

What does the therapy ward in the Clinic for Nuclear Medicine offer you?

The therapy station of the Clinic for Nuclear Medicine is located on the 2nd floor of the Karl Lennert Cancer Center (House 50, directly on Feldstrasse 21) on the UKSH's Kiel campus. Our ward has eight beds (4 single rooms and 2 double rooms).

The entire station area is in accordance with the above. statutory provisions a so-called control area, in which, apart from the patient, only nursing staff who have been specially trained in radiation protection law guarantee patient care. Patients are looked after around the clock by a dedicated and competent 10-person care team.

The anamnesis as well as the physical examination on the day of admission and the actual therapy capsule administration with a discussion of the findings on the day of discharge are carried out by the responsible ward doctor. In addition to the daily rounds, a weekend round is carried out by the doctor on duty. For reasons of radiation protection, the nursing staff and the ward doctor will always keep their distance from you for the duration of the inpatient stay and reduce the conversation time to a minimum.

As part of your daily visits, your dose rate is determined by means of a dosimeter measurement. Depending on the course of the measured values, the discharge will then also take place, which will be announced to you in good time so that you can organize your pick-up or the drive home without any problems. Personal items such as books and writing utensils as well as handicraft utensils, puzzles or notebooks are allowed. These are not "irradiated".

It is also possible to activate a telephone card for a fee of at least € 20. With this card you can then also listen to television and radio.

Please bring all medication (or the corresponding medication package leaflet) that you usually have to take regularly with you to the inpatient admission, as not all medication may be immediately available on the ward.

What are the risks and side effects during and after radioiodine therapy?

Due to the biological properties of stable, non-radioactive iodine and the physical peculiarities of “hot”, i.e. radioactive iodine-131, there is only a low level of radiation exposure of the organs that do not absorb radioiodine. In the context of large-scale studies z. B. by Per Hall 1992 (The Lancet Vol. 340, 07/1992) with over 45,000 patients and Elaine Ron 1998 (JAMA 1998, 347-55) with over 35,000 patients showed no increased cancer mortality in patients treated with radioactive iodine. Acute side effects are rare:

Naturally, with the accumulation of iodine-131 in the thyroid tissue, a so-called radiogenic inflammation occurs, which can occur within 2 to 5 days after taking the therapy capsule and is usually symptom-free.

In rare cases, depending on the underlying thyroid disease, local symptoms in the front of the neck (e.g. a feeling of pressure or sore throat) and, much less often, ear pain may occur.

In addition, other types of serious long-term effects are very rare overall. Depending on the administered activity of the therapy capsule, there may be a possible reduction in tear or saliva secretion with corresponding dryness of the eyes or mouth.

Finally, there is the rare side effect of so-called autoimmune stimulation with the development of a secondary, i.e. H. The following autoimmune disease of the thyroid should be mentioned after radioiodine therapy due to thyroid autonomy a few weeks after the actual radioiodine therapy, which can then be treated with a second radioiodine therapy, depending on the patient's wishes.

To be on the safe side, we recommend that patients consistently use contraceptive measures for at least 6 months, women of childbearing age should use contraception for at least 6 months. In the case of an existing pregnancy or if you are about to have children after radioiodine therapy, radioiodine therapy is contraindicated.

What is the radioiodine therapy procedure?

1st day - recording day

Inpatient admission (from approx. 10:00 a.m.) with physical examination and blood sampling as well as checking of the findings documents for completeness. The capsule application takes place between 2 p.m. and 4 p.m. after the thyroid laboratory parameters have been checked.

Inpatient following days and discharge day

As part of the morning rounds with checking of the condition under the radioiodine therapy, the dose rate is determined once a day by the ward doctor using a dosimeter at a distance of 2 m. The patients are instructed by the nursing staff at the so-called uptake measuring station to document the radioiodine uptake in the thyroid gland. The patients carry out the measurement independently on the following days; of course, the nursing staff will help in the event of any difficulties.

On the day of discharge, so-called full-body and detailed scintigraphy is performed in the diagnostic department on the 2nd basement floor. These will be discussed with you by the ward doctor.

In the discharge interview with the ward doctor or in the discharge letter, the appropriate follow-up appointments are agreed and the further course of action regarding behavior after radioiodine therapy, also in accordance with the applicable radiation protection aspects and possible thyroid medication intake, is discussed.

Contact person and responsible for queries

Clinic for Nuclear Medicine, Molecular Image Diagnostics and Therapy
Come on. Director, specialist for Diag. Radiology and nuclear medicine, doctor for palliative medicine
Phone Kiel: 0431 500-16800


Clinic for Nuclear Medicine, Molecular Image Diagnostics and Therapy