Initial Treatment

  • If you (want to) become pregnant, you should discuss this with your doctor who can advise you on local guidelines.

    The guidelines applicable for the UK require use of a condom for seven days after treatment with radioactive iodine, and a reliable form of contraception for 6 months afterwards, before trying to become pregnant. Males are advised not to father a child for at least 4 months after treatment.
    It is important not to breastfeed while having treatment with radioactive iodine – the usual advice is to stop 6-8 weeks before treatment and not to breastfeed afterwards.
    Your doctor will monitor you more closely than usual because your body will need more thyroid hormone as your pregnancy develops. Your doctor will adjust the dose of your thyroid hormone replacement as required. In addition, an iodine supplement will be recommended during the early weeks of pregnancy, as only after around 12 weeks does the embryo develop a functioning thyroid gland.


  • In general, you can expect to be in hospital for between 1-3 days, depending on the extent of surgery. You should avoid heavy lifting and strenuous activity until your wound has healed; your neck will feel stiff at first but this will gradually improve. Returning to work should be possible within 2 weeks, but discuss this with your doctor.

  • Acute side effects of ingesting high doses of RAI mostly consist of swelling in the surgical area as a result of iodine uptake in thyroid tissue remnants, with occasional swelling of the salivary glands and stomach discomfort. To prevent salivary glands damage, you will be advised to drink a lot of water and to chew chewing gum. Other side effects are reduced taste and lacrimal duct disorders. 

    Whether or not chronic side effects develop at a later stage depends on the number of radioactive iodine treatments you receive altogether, and on the total activity of the radioactive iodine administered. 

    In men who still plan to have children and are expected to require several radioactive iodine treatments, sperm cryopreservation may be a sensible measure, as large amounts of radioactivity, for example as a result of multiple treatment courses, may decrease sperm count. Although this effect is transient in most cases, it can sometimes be permanent. For women, menstrual irregularities can occur in up to 30% of people. For pregnancy advice, click here.

  • The success of ablative radioiodine therapy relies on sufficient uptake of radioactive iodine (RAI) into residual thyroid cells. This mechanism will improve by high levels of thyroid stimulating hormone (TSH), as TSH will stimulate the remaining thyroid cell to take up (radioactive) iodine. If you are hypothyroid (i.e. you have very low levels of thyroid hormone), the production of TSH in the body is massively increased which in turn means that residual thyroid tissue takes up as much radioactive iodine as possible.

    Your doctor should discuss with you which of the following two approaches is most suitable to stimulate the TSH levels in your body;

    1. Withdrawal of your thyroid hormone tablets

    2. Administration of 2 injections of bioengineered TSH (rhTSH)

  • When you go home after treatment with radioactive iodine, you should avoid close contact with babies, young children and pregnant women, and avoid long periods of contact with other people. This may mean staying away from crowded areas such as the cinema, where you could be in close contact with someone else for a long time. The staff at your treatment centre will tell you how many days you need to continue with this, as it will depend on the dose of iodine you receive and how much contact you might expect with young children.


  • This involves stopping your thyroid hormone replacement tablets immediately after thyroid surgery and waiting for your TSH levels to rise – this usually takes 2 to 6 weeks. During this time you may experience one or more symptom of hypothyroidism such as feeling listless and tired; you might suffer from bouts of fatigue, and may experience difficulty concentrating.  Some patients also struggle with depression and memory. You may need to take time off work during this phase of your treatment.

    Signs of hypothyroidism

    Hypothyroidism Side Effects

    Administration of TSH (rhTSH)

    This involves a rapid and short-term increase in TSH levels through administration of rhTSH (recombinant human TSH), a bioengineered substitute for natural TSH. rhTSH is administered by intramuscular injection (in the buttocks) on the two days before you take your radioiodine capsule for RAI. It’s not needed to stop taking your thyroid hormone replacement medication in this instance. In some cases, but not always, you will be asked to minimise iodine in your diet for 2-3 weeks before RAI administration. 
  • The first step is the surgical removal of the affected thyroid gland and surrounding tissue.
    The next treatment step involves what is called radioiodine ablation therapy, or RAI for short. Despite surgical removal of the thyroid, its delicate position means that some residual thyroid tissue is nearly always left behind and it is important to make sure that all the cancer has been destroyed in order to reduce the risk of tumour recurrence.

    In general thyroid cancer is treated with surgical removal of the thyroid followed by therapy with radioactive iodine, but for advanced thyroid cancer, palliative chemotherapy and targeted therapies are treatment options.

    A further treatment step involves taking thyroid hormone tablets to replace the natural hormones your thyroid used to supply. You should expect to take these for the rest of your life.

    The aim of initial therapy is to eradicate all residual thyroid cells through surgery and ablation, in order to reduce the risk of local and distant tumour recurrence which could prolong survival. Ablation increases the sensitivity of any necessary subsequent iodine scanning and subsequent Tg monitoring, which help your doctor be sure that the thyroid cancer has been fully destroyed when you come back for follow up.