These notes give you a little background information, and contain some practical hints to avoid any possible risk to others during the treatment.

Transcription

1 Treatment of thyrotoxicosis with radioiodine These notes give you a little background information, and contain some practical hints to avoid any possible risk to others during the treatment. What is thyrotoxicosis? This is a general term for diseases of the thyroid gland in which the thyroid produces too much thyroid hormone. Thyroid hormone is needed for many body processes, however excess of this hormone means the processes tend to run too fast. This can produce many symptoms including rapid heart rate, muscle tremor, bowel upsets, undue sensitivity to heat and dry, sore eyes. Commonly the condition results in weight loss and exhaustion. What are the treatment options? There are three main options; surgery, where part or all of the thyroid is removed, drugs that block the effects of the excess hormone (the most common of these is Carbimazole, but there are several alternatives) and treatment with radioiodine. How does radioiodine treatment work? Radioiodine treatment like surgery is a permanent fix, without any need for hospital stay, surgery or residual scar. The medication is radioactive, so there is slight risk to other people around you if you do not take sensible precautions for a few days after treatment. This treatment will expose you to some radiation and there is a theoretical risk associated with this exposure (just as there is for ordinary X-rays) however the risk is very low. The treatment has been used for over 50 years, and no measurable ill-effects from the radiation have been reported. Iodine is found in many foodstuffs and is an essential part of our diet. The thyroid concentrates iodine from blood and uses it as raw material to make thyroid hormones. Radioiodine is concentrated in the same way as ordinary iodine, so most of the radiation from the radioiodine is absorbed by the thyroid. The radiation disrupts some of the cells in the thyroid, resulting in a portion slowly dying off. Reducing the number of cells in the thyroid reduces the production of thyroid hormone, so the levels in your body slowly fall. The radioactivity clears quite quickly, most being gone in a few days however it takes much longer for the reduction in thyroid cell numbers to have an effect. This is not an instant cure; the process will take many weeks so you will see a slow but steady improvement. Are there any reasons why I can t have radioiodine treatment? Allergies to iodine are not a barrier to treatment. The amount of iodine is given less that 1/1,000,000 th of a gram, insufficient to produce an allergic reaction. If you have had, or are currently taking any of the following they may affect your treatment, and need to be discussed with your doctor: Thyroid medication Some types of health foods, particularly keep tablets and some dietary supplements Some types of X-ray contrast agents ( dyes ) Some types of heart and blood-pressure medication If in doubt, make a list of medication you are taking, or bring your medication with you when you see your doctor or when you come for treatment.

2 If there is any possibility that you are pregnant it is likely you will not have the treatment. This is because it is impossible to stop the baby s thyroid being treated at the same time as yours; which would permanently impair the baby s thyroid. If you are unsure as to your pregnancy status, tell our staff before treatment. Pregnancy should be avoided until six month after radioiodine treatment. If you are breast feeding you will need to defer treatment or stop breast feeding since your breast milk will contain a little of the radioiodine after treatment, and this may affect your baby s thyroid gland. Are there side-effects? The most important is that your thyroid gland might stop functioning entirely following treatment. You will be monitored closely to ensure that appropriate replacement therapy is prescribed when and if this occurs. For most people this takes the form of a sing thyroxine tablet taken daily. You may notice a dry mouth or mildly tender thyroid for a time after treatment but this will disappear in a few days. Thyroid disease can affect your eyes, and radioiodine treatment has been known to worsen this affect for a short time. Your doctor may prescribe drugs (steroid) to prevent this. If you already have symptoms from your thyroid disease these may be worsened for a short period after treatment, and your doctor may advise some additional medication during this time. How can I expose other people to radiation as a consequence of my treatment? There are two aspects to this. Firstly some of the radiation from the radioiodine escapes from your body just like X-rays. If you are close to other people they will be exposed to this escaping radiation just as they would be to X-rays. The further you are away, the lower the intensity of exposure. In practical terms if people are more than 1 or 2 meters away, the intensity is so low that may be ignored. Secondly your thyroid uses only part of the radioiodine; the rest is eliminated from your body. Most of this is eliminated in the first day or two via your urine, and a very small amount is eliminated over a slightly longer period (a week or so) via your perspiration and nasal secretions. It is possible that some of this material can be transferred to other people (for example, you use your towel after a bath, transferring a little of your perspiration containing radioiodine onto the towel; someone else uses the same towel afterwards, transferring the radioiodine to their skin). This could result in their thyroids also receiving some radioiodine, and thus being inadvertently treated fir a disease they don t have! Note: That the radioactive component dies away naturally so while you may need to take some precautions to avoid exposing others, these are for a few days only after treatment. What will happen to them if they are exposed? The level of exposure is low and will not produce any perceptible effects. There is a theoretical long-term risk since any exposure to radiation increases the risk of damage to body tissues and has a theoretical risk of possible later cancer it doesn t matter if the radiation is from radioiodine, X-rays or sunlight, all increase this risk. Although the risk is very low in fact so low that no effects have ever been demonstrated from this form of treatments, we try to minimise even this theoretical risk where we can. We do take particular care to avoid exposing young children or anyone who is pregnant. This is because babies are more sensitive than adults to many environmental risks so we adopt a more cautious approach to radiation exposure.

3 What precautions do I need to take? As everyone is different, specific precautions need to be adjusted to fit your circumstances. These will be discussed with you at the time of your treatment; however there are some general things you need to consider beforehand. These are: Time away from work: You may need to take a few days off work after the treatment. It is difficult to say exactly how long since it depends on the nature of your work and the amount of radioiodine your doctor has prescribed for you, but most people will need to take somewhere between 2 and 5 days off work. This time can be reduced if you work on your own, and you can choose to have your treatment on a Friday, or prior to days off work. Care of Children: If you are taking care of very young children at home, or someone in your household is pregnant then you may need to make arrangement to reduce their exposure to radiation. Again it is difficult to be precise since circumstances differ, so you should discuss this with your doctor prior to treatment. Sleeping arrangements: You should change sleeping arrangements for the first 2 3 days after treatment (eg; by sleeping in a spare room or on a temporary bed) to avoid exposing your partner. Attending public functions: You should not attend any public meetings, going to movies or shows or take long (more than 5 hours) trip on public transport for a few days after treatment since you could find yourself in close proximity to others for long periods. Shopping: You will be able to go shopping and to make short trips on public transport since these will not involve extended periods close to others. Hygiene: A small amount of the radioiodine comes out in your perspiration and nasal secretions over the first few days after treatment. Some will get on your clothes (particularly underclothes), towels and handkerchief. To eliminate any possible risk to others make sure no-one else uses your towels for the first 5 days after treatment and wash your towels, underclothes and handkerchiefs separately from other laundry. Toilet arrangements: Any radioiodine not used by your thyroid is cleared by your kidneys as body waste. This means your urine is slightly radioactive for 2-3 days after your treatment. You will not notice this, but it can be a potential source of risk to others. Ensure that any urine spills are promptly wiped up, and men should urinate sitting down to minimise possible spills or splashing. After using the toilet flush the toilet at least twice to rinse away any residual urine. If there are urine spills, clean them up with toilet paper and dispose of this in the toilet, then wash your hands. If you live in a remote area and have a septic tank or other closed sanitation system, please let us know and we will give specific instructions to avoid possible hazard.

4 Food & Drink: We would advise you to drink a little more fluids than usual for the first two days after treatment. This helps to clear any excess radioiodine from your body. Other than this you can eat & drink normally after treatment, and consumption of alcohol will not affect the treatment. If you are preparing food for others during the first few days, ensure you wash your hands before touching the food. Existing health problems: If you have other health problems, particularly problems with urinary continence, or suffer from frequent nausea please discuss this with your doctor. We may need to make some special arrangements for your treatment. Pets: There is no risk to pets from the radioiodine, so you do not need to make special arrangements for their care. How is the treatment given? The radioiodine is dissolved in 30 mls of water (about ¼ cup) and you drink it through a straw. This solution has little or no taste, so don t worry about it tasting of iodine. If you have difficulty in drinking through a straw tell us beforehand and we will make alternate arrangements. What will happen afterwards? You may get a dry mouth & slightly sore throat for a few days after treatment. This is perfectly normal, and is a sign that the radioiodine is doing its work. This should subside by itself within a week or so, but if you find it uncomfortable any of the common pain-killers (for example aspirin or paracetamol) will relieve the discomfort. It is possible your thyroid symptoms become more noticeable for a short time after treatment. This is also quite common. If you find these symptoms distressing please contact your doctor or the Endocrine Unit (see below for their phone number) for advice. You may need to take additional medication for a short time after treatment. Your doctor will advise you if this is needed. You will need to have a blood test about 4 weeks after treatment, and you will need to see the Endocrine doctor shortly after this. It is important to keep this appointment, since the doctor needs to check on your progress and plan any further follow-up. Your thyroid may go under-active after treatment. This will make you feel rather sluggish and sleepy. If this does happen your doctor will probably advise taking additional thyroid hormone in tablet form to top up your level. It is also possible that you may need some further treatment to bring your thyroid fully under control. In this case a further dose of radioiodine may be advised. What are the chances of needing more than one treatment? This is a bit dependent on the underlying thyroid disease for which you are receiving your radioiodine treatment and the dose of radioiodine that has been prescribed for you. On average a further treatment is required in about 25% of patients.

5 What are the chances of my thyroid becoming underactive? Again this depends on the dose of radioiodine that has been prescribed, but has been estimated to occur in approximately 80% of patients sometime in the seven years following treatment. Who do I contact for more information? The best source of information is your own doctor; however you may contact the Endocrine Unit on (04) extension 5237 if you need additional advice. If you wish to discuss any aspects of the treatment process itself, please feel free to contact the Department of Nuclear Medicine on (04) extension 5246.