Occupational Health Clinic
September 27, 2011

When patients are treated with radioactive iodine, their blood and body fluids such as urine and vomit can contain the radioactive drug. Caregivers should understand the risks of exposure. There are two different types of radiation risks:

  • Thyroid exposure: Having the radioactive iodine absorbed by your thyroid gland.
  • External beam radiation: Getting radiation exposure from the contaminated body fluids, just like you would from an X-ray.

Preventing thyroid exposure

If taken internally through the mouth, skin or lungs, radioactive iodine can be absorbed by the thyroid gland, leading to an increased risk of hypothyroidism and benign (non-cancerous) thyroid adenomas (growths.) Radioactive iodine does not cause hyperthyroidism, goiter, Grave's disease or thyroid cancer.

The healthcare worker can prevent thyroid uptake of radioactive iodine by wearing personal protective equipment, and by using safe practices to keep from accidentally getting the patient's blood or body fluids in their mouth, nose, or on their skin. Safe practices are:

  • Wear a gown and gloves when caring for the patient.
  • If there is a risk of splash, wear a mask with eye protection.
  • Do not take your own food or drink into the patient's room.

Exposure is limited by controlling who can go into a patient's room and by ensuring that caregivers wear the appropriate protective gear.

In the past, Vanderbilt performed bioassays on all nurses who cared for patients on radioactive iodine. Program results showed no significant exposures occurring, so mandatory testing was discontinued. Though discontinued, this testing is still available for caregivers who have had an exposure incident. Testing is administered by Vanderbilt's Environmental Health and Safety Department.

Preventing external beam radiation exposure

Like all radioactive materials, radioactive iodine emits external beam radiation. We all get some radiation exposure daily from the sun and appliances used around the house.

The medical risk of overexposure to external beam radiation includes acute radiation sickness (for massive overexposures) and malignancies (primarily leukemia and other hematologic malignancies) from chronic overexposure.

Since the patient is ingesting the full radioactive dose, they have much more risk than the healthcare worker. Researchers have studied these patients to learn their risks after treatment. There is no increase in the incidence of leukemia or cancer and no increase in overall cancer mortality.

Most radioactivity is concentrated in the patient's body fluids. To limit healthcare worker exposure to radiation, the patient's body fluids are contained and covered to contain radiation. Staff must wear their gown and gloves when handling body secretions.

The amount of radiation exposure is measured with dosimeter badges. OHC recommends that caregivers wear their badges whenever caring for a radioactive iodine or brachytherapy patient, and remember to turn their badge in for exposure level measurement.

Keywords: radiation, radioactive iodine, radioiodine, I-131, thyroid