Radioactive Iodine Precautions and Side Effects
There are both regulatory (by-law) and medical precautions to using radioactive iodine (RAI).
The regulatory precautions are regulated by each state. They dictate if treatment can be performed in the outpatient setting or if the patient needs to be admitted to the Hospital and placed under radioactive precautions. Prior to leaving the Hospital, the nuclear medicine department and your thyroid treatment team will discuss the precautions and review ways to decrease the side effects and risks of exposure after receiving radioactive iodine.
The medical precautions are for the caregiver and family as well as the patient. Since I-131 produces radiation, patients must do their best to avoid radiation exposure to others, particularly to pregnant women and small children. Medical precautions will be given to you during the "pre-ablation" or "pre-RAI treatment" appointment. These precautions are very specific and should be followed as closely as possible to reduce potential exposure to others and to decrease the likelihood of short- and long-term medical complications associated with RAI.
Side effects of RAI treatment
All medical treatments have side effects; RAI is no different. In previous years, the goal of therapy was to get rid of all thyroid cancer cells no matter the total dose of RAI. With increased awareness of the potential risks associated with RAI, the current approach attempts to more carefully balance the risks and benefits of treatment.
RAI therapy is associated with short- and long-term medical risks, including:
- Nausea within the first few hours of taking the dose (frequently managed with anti-nausea medication).
- Inflammation of the salivary glands. Symptoms usually include decreased production of saliva leading to a dry mouth (called “xerostomia”) and subsequent decreased taste as well as an increased risk of developing dental cavities. Strict dental hygiene with brushing, dental floss and fluoride mouthwash may help decrease the risk of cavities.
- Permanent salivary gland problems may occur in up to 15 percent of patients. The use of sour candy or lemon juice, starting 24 hours after RAI dosing, along with vigorous hydration for three to five days may help protect the salivary glands as well as ensure that the RAI is cleared from non-thyroid cells as quickly as possible.
- Decreased lung function in patients with a history of thyroid cancer that has metastasized to the lungs. This change may be due to the presence of the cancer or a side effect of the RAI treatment. Pulmonary function testing (PFT) should be followed for all patients with a history of papillary thyroid cancer (PTC) that has spread to the lungs.
- Temporary or permanent decrease in blood cell counts.
- Increased lifetime risk of developing second, non-thyroid cancers in patients exposed to RAI compared to those who were not, to include cancers of the blood system (leukemia), salivary gland, urinary system, gastrointestinal and others.
- Special concerns for women:
- Temporary menstrual irregularities have been reported in up to 17 percent of females under the age of 40 years, 65 percent of whom were treated with a single dose of RAI. For patients interested in starting a family, there does not appear to be an increase in infertility or birth defects in pregnancies after RAI. However, it is recommended to avoid conception during the year after a large RAI dose to decrease the chances of a miscarriage.
- Special concerns for men:
- In boys who have completed puberty, there may be a temporary increase in one of the hormones that regulates the function of the testes (follicle stimulating hormone; FSH). For the majority, this is temporary and will be unnoticed except for the blood test abnormality. However, several doses of RAI may lead to decreased sperm counts and temporary infertility. Testosterone production is generally not affected. Males should avoid attempts at conception for at least four months after RAI treatment. Sperm banking may be recommended for patients who are expected to need several doses of RAI for thyroid cancer.
The Pediatric Thyroid Center at CHOP is committed to determining which patients will or will not benefit from RAI therapy. You, the patient and family, are important members of the treatment team. Be informed and be involved. Know the risks and the benefits of the treatment being recommended and the expertise of the center providing your care. The potential risks of complications decrease if you receive care in a center dedicated to the care of pediatric patients with thyroid disease.
Ongoing care and research at CHOP
Learn about our commitment to thyroid disease research and finding new treatments.