Radio-Iodine Therapy

Following your consultation for Radio-Iodine therapy, please read the following information prior to the treatment.

What is radio-iodine treatment?

Your consultant has asked us to see you about iodine (iodine 131) therapy for thyrotoxicosis. Iodine therapy uses a form of iodine that is radio-active. Iodine is taken up by the thyroid gland and the radioactivity will ‘slow down’ the thyroid’s production of certain hormones.

Radio-iodine has been used for treatment for over 50 years, and has been shown to be both safe and effective. We have been using radioactive iodine therapy in this Department for many years and are highly satisfied with the results. 

How is treatment given?

The treatment is given as a radio-active iodine capsule. After the treatment you will need to wait in the Nuclear Medicine Department for approximately 30 minutes to ensure that the capsule has been absorbed. A hot drink of tea or coffee will be needed to aid the further absorption of the capsule when you leave the hospital.

Is there any preparation before the treatment?

Yes and it is important to follow the instructions exactly otherwise the treatment may not be effective.

  • Medication – You must tell us about all the medication you are taking, even health products or supplements bought over the counter.
  • It will be necessary to stop taking certain medication before the treatment – for example carbimazole (CBZ) and propylthiouracil (PTU) must be stopped at least three days before the treatment. 
  •  Food – Do not eat any fish or seafood for 3 days before the treatment. Please see the paragraph on low iodine diet for more information.
  • On the day – You may have a light breakfast but no lunch. You should drink normally.

Can I have the treatment if I am pregnant or breast feeding?

In cases of pregnancy, NO. Women who are pregnant must not be given radio-iodine. If there is any possibility that you may be pregnant, you must tell us. You will be asked to fill in a questionnaire just before the treatment to give us some more information in relation to whether you could be pregnant. You are advised not to become pregnant for at least 6 months following the treatment. You must take adequate contraceptive care.

If you are breastfeeding you will be asked to stop breastfeeding completely after the treatment.  Therefore it is extremely important that you tell us if you are breastfeeding so that we can discuss with you whether this is the best treatment option.

Will there be any danger to my family or friends?

We wish to keep all radiation levels as low as reasonably practical. We aim to ensure that your family and friends will not receive radiation exposure above the levels experienced by members of the public in their daily lives. We will discuss in detail how we can achieve this.

The essential precautions to reduce radiation exposure to others are:

  • Avoid non-essential close contact with babies, young children and pregnant women. For people with day to day contact this can be for a period of 2-4 weeks. At consultation we will discuss how this can be practically carried out.
  • You may need to take some time off work depending on your specific job
  • You will need to avoid close contact with other people for several days
  • You must sleep alone for approx 1 to 2 weeks after treatment
  • Women should not become pregnant nor men father a child in the 6 months after treatment
  • Usually there will be no restriction on travel by public transport but we will discuss this further with you. Please inform us if you plan to fly within 3 months of the treatment date as we will need to give you some further instructions. 

On the day of the treatment you will be given clear instructions regarding the time-frame that you will need to observe these precautions. The exact length of time for which these precautions apply depends on the amount of radioiodine the doctor prescribes and your contact patterns with other people.

Are there any side effects?

Very occasionally after receiving the radio-iodine you may get a sore throat. This should last for only a few days and if it does happen to you, it can be relieved by some Paracetamol.

You are likely to become hypo-thyroid. This could happen within a few months or many years after the treatment. Blood tests will check the state of your thyroid. If it does become underactive, you will be given thyroxine tablets.

Your thyroid may become overactive once again. In this occasion, a further radio-active dose may be considered.

What should I do if I cannot keep my appointment?

Please contact the Nuclear Medicine Department if you are unable to keep an appointment. The radio-iodine has to be ordered specially for each patient and it would be appreciated if any unavoidable appointment cancellation or rearrangement could be made at least one week before the appointment date so that the order for your dose can be changed accordingly.

Low iodine diet before Radio-Iodine treatment

An iodine-rich diet can reduce the effectiveness of the treatment, so it is advised to not eat :

  • Food artificially coloured pink or red (as the colouring is iodine-rich) such as: Canned and glace cherries; Canned strawberries, Salami; Pastries and sweets
  • Cough medicine
  • Iodised table salt, sea salt                          
  • Vitamin or mineral supplements (many of these contain iodine)
  • Seafood, including shellfish, fish, kelp and seaweed

Cut down on

  • Dairy products such as: eggs, cheese, milk and milk products

These dietary precautions should be followed up until the time of the treatment and 2-3 days after.

If you have any questions or concerns please do not hesitate to call the Nuclear Medicine Department.

Contact information

Chelsea and Westminster Hospital

Nuclear Medicine Department
T: 020 3315 8415

Contributors
Liz Alden George Vasilopoulos