Radioiodine Therapy

Radioiodine therapy uses a radioactive form of iodine to treat hyperactivity or enlargement of the thyroid gland. The iodine is contained in a small capsule which is swallowed and digested in the stomach, then absorbed by the thyroid gland. It is a safe alternative to surgery or long term medication.

After you undertake radioiodine therapy you will receive advice on how to avoid giving unnecessary radiation exposure to others.

Before your procedure

What to bring

  • Your referral form
  • Any relevant previous imaging
  • Your Medicare card and any concession cards
  • All of your current medications in their containers


A referral from your doctor or medical specialist, and an appointment is required for this examination.

Before you attend your appointment, please read and follow the printed instructions given to you by your referring doctor or medical specialist exactly.

When making the booking, a technologist will speak to you to gather information and explain the procedure.

You must cease thyroid medication as instructed before the appointment date.

On the day of your appointment you must eat nothing for three hours prior to the appointment, but you may drink water. After the appointment you must eat nothing for a further one hour.

If you are a diabetic please advise Lake Imaging when making your appointment in case special fasting arrangements are necessary. 

Please ensure that you make arrangements to comply with the radiation precautions you were given. These will vary for each patient.

Be sure to notify us promptly if you need to reschedule or cancel your appointment, as the capsules are manufactured to individual order, and require 48 hours to cancel.

Please allow at least 30 minutes for the complete procedure. 

During your procedure

What to expect during my procedure

When you arrive for your appointment at Lake Imaging a technologist will explain the radioiodine therapy procedure, then a doctor will interview you and discuss your therapy. The technologist will then give you the radioactive capsule to swallow, along with any final instructions.

Risks and side effects

Nuclear medicine procedures are considered very safe, but exposure to low doses of gamma and beta radiation carries an extremely small theoretical risk of future cancer formation.  Although the radiation dose from this therapy is higher than for diagnostic scans, extensive research has not found any evidence of increased cancer incidence in patients receiving radioiodine therapy. In all cases, any potential risk is balanced against the benefit of the treatment, and radiation doses are reduced to a level as low as reasonably achievable.

Other minor, transient side effects are possible. These include dry mouth and difficulty in swallowing. The doctor will fully discuss this with you before giving you the capsule to swallow.

Occasionally a second treatment may be necessary after several months, or the thyroid gland may become underactive after a number of years.

Any continuing side effects or concerns should be discussed with your referring doctor or medical specialist.

Who will perform and report my examination?

At Lake Imaging all radioiodine therapy procedures are performed by a Nuclear Medicine Technologist registered with AHPRA (Australian Health Practitioner Regulation Agency), and a credentialed radiologist or physican interviews the patient, reviews relevant medical history, and other imaging, before the treatment proceeds

After your procedure

What to expect after my procedure

After your appointment is completed you will be able to go home and continue most activities as normal.  Depending on the amount of radioiodine given, you should avoid contact with pregnant women and small children for two to five days, and avoid long periods of close proximity to adults for several days.  We may also ask you to avoid preparing food for others, and recommend sleeping during this period. Restrictions on returning to work may also apply, and will depend on the type of work you perform and the dose you have received, but is normally no longer than three days.

How do I receive my results

A report detailing your treatment will be forwarded to your referring doctor within 48 hours.