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Guidelines To Radioactive Iodine-131 Patients

The thyroid gland

What is radioiodine-131 therapy and how is it used?

Radioiodine-131 therapy is the treatment for patients who have an overactive thyroid gland, a condition called hyperthyroidism due to Graves’ disease which produces excessive thyroid hormones.

Nuclear medicine can be used for imaging as well as therapeutic purpose using a small amount of radioactive source to diagnose or to treat various diseases including cancer, cardiac disease and certain abnormalities in the human body. The thyroid gland produces two hormones that process the overall body metabolism via a chemical process which convert food to energy. When the thyroid gland is overactive it will excrete more hormones thus increasing the rate of metabolism.

Radioactive iodine-131 is a radioactive isotope producing ionising radiation that can be used for medical purpose. When a small amount of radioactive iodine-131 is given to a patient it is absorbed by the body with a high concentration in the thyroid gland, thus destroying the thyroid gland cells as well as the cancerous cells.

Who is involved in this procedure?

The nuclear medicine physician who has undergone special training in the field of nuclear medicine with expertise in endocrine, oncology, thyroid surgery and radiation protection.

Is there any medical equipment used?

There is no medical equipment used during the radioactive iodine-131 therapy.

Since there is no medical equipment used, the patient is required to drink the radioactive dose that has been prepared.


Iodine-131 is an unsealed radioactive source with a half-life of 8.04 days.It emits gamma and beta rays. The beta rays contribute to the absorbed dose to the organ that absorbed the radioactive iodine.

Instructions To Patients

Stop taking (T4) thyroxine within 20 days before admission.

For patients who are on T3, they must stop it within 10 days before admission.

Patients to be given thyroid hormone injection alternately once in 3 days for the purpose of increasing the intake of iodine-131.This is to be done 3 days before admission.

Precautions During Treatment

Any symptoms of diarrhoea or constipation have to be taken into account before admission. These symptoms can be hazardous, because if the wastes are not properly handled it can contaminate the treatment area.

If the patient vomitted or urinated 3 days after taking the radioactive iodine, it must be cleansed with the cooperation of the Radiation Protection Officer of your hospital. Anyone living with the patient who may be contaminated by the waste must be examined and the level of contamination to be measured.

  • If the patient is in a life threatening situation, the officer on duty should not delay any effort in saving the patient. For example if there is a fire, remove the patient to safety from the burning house. Contact the Radiation Protection Officer to ensure the radiation safety of the patient, staff, public and the environment.
  • When an iodine-131 patient died, the Radiation Protection Officer must be contacted to ascertain that the level of exposure is low. The Radiation Protection Officer is required to monitor the exposure emitted by the patient’s body before the caretaker is allowed to attend to the corpse. At the same time proper advice must be given to the patient’s kin or caretaker with regard to the appropriate procedure in handling the corpse that has been contaminated with radioactive material.

When Patient Experience Pain And Constipation

  • If the patient is constipated, advise patient to take laxative such as Gravol.
  • If the patient experiences no sign of peristaltic movement of the bowel within 24 hours of iodine-131 treatment, advise the patient to take milk or magnesia.
  • Contact a doctor if the problem persists.

Increasing The Intake Of Fluid And Sucking Candy

  • In order to reduce the level of radioactive iodine in the patient’s body, it is recommended that the patient drink plenty of water after treatment for 2 days so that the accumulated radioactive waste in the bladder could be removed expediently.
  • The patient is also advised to suck candies so that the radioactive waste can be removed via the saliva
  • These guidelines is dependent on the patient’s medical history. Discuss with your Physician before:
    • Sucking candies.
    • Drinking plenty of water.

Example Of Consent Before Treatment

Important Precautionary Measures At Home

Important factors are distance, time and hygiene.

  1. Distance

    The further away is the distance between you and your family member, the less amount of exposure your family member received.


    Distancing yourself from the others will reduce the amount of exposure to ¼ of the dose that you received.

    What you have to do:-

    • Sleep alone.
    • Sit alone whether on a sofa or in a car.
    • Sit furthest from the driver in a car.
    • Do not use public transport.
    • Do not go to the movie or receptions.
  2. Time

    Avoid spending more than 2 hours beside a female of child-bearing age and small children.

    Avoid spending long time with your family because that will increase the exposure to them. This is important to children and female of child-bearing age, for 7 days after treatment.

    Whenever you are among the public, reduce the time as follows:

    You may spend your time with your family members at a distance of 4 meters.

    • 45 minutes per day at 1 meter
    • 2 hours per day at 2 meters
    • 7 hours per day3 meters
  3.  Hygiene

    Practicing good hygiene can minimise the rate of contamination left by the patient’s body. In view of the fact that the waste is produced via a natural process, the toilet used must be cleaned immediately and the hands washed thoroughly at one place and wiped using tissue to avoid contamination.

    • Set aside a washroom to be used ONLY by you. This is very important so as to avoid sharing of personal items such as toothbrush, toothpaste, towel and what else in the washroom.
    • Wash hands thoroughly with soap and plenty of water each time after using the toilet.
    • Bathe at least once a day.
    • Clean your own toilet after use.
    • Male patients are advised to use sitting toilet while urinating so as to avoid urine splash stray.
    • Flush your toilet three times after each use
    • Clean the sink, toilet, shower and water residue after each use.
    • After brushing your teeth, you are advised to spit into the toilet bowl and flush it twice.
    • Flush all the tissues down the toilet bowl.
    • Do not take chewing gum.
By following these simple guidelines for 5-6 days consecutively after Iodine-131 treatment you are not endangering the public as well as the affected family members.


  1. http://www.hsc.wvu.edu/rsafety/MediaLibraries/RSafety/Media/Documents/pdf/radioiodine.pdf
  2. http://www.stjoes.ca/media/PatientED/F-J/PD%206177%20I131RadioactiveIodineTherapySJH-trh.pdf
  3. http://www.epa.gov/rpdweb00/radionuclides/iodine.html
  4. http://books.google.com.my/books?id=M1UVAAAAIAAJ&pg=PA233&dq=guideline+of+taking+iodine-131&hl=en&sa=X&ei=GrjVUe3mBYmMrQeRzIHgDw&ved=0CDIQ6AEwAQ#v=onepage&q=guideline%20of%20taking%20iodine-131&f=false


Last Reviewed : 9 January 2014
Writer : Adzlin Hana bt. Mohd Sari