Medical societies, experts dismiss radiation exposure from radioiodine as a public health concern

Existing data do not support that the public is at risk due to outpatient thyroid treatment.

In late October, The Endocrine Society, American Thyroid Association, Society of Nuclear Medicine and American Association of Clinical Endocrinologists released a joint statement backing current procedures for the release of outpatients having undergone treatment with radioiodine, or ¹³¹I, stating that the current outpatient procedure, “based on scientific evidence, is safe for patients, their families and the public when radiation safety instructions are followed.” However, the associations qualified their statement, adding that should data emerge that indicate there is a safety concern, the issue should be re-examined.

The release of this statement was prompted by a meeting of the Nuclear Regulatory Commission (NRC) that was scheduled to examine the use of medical isotopes, such as radioiodine, and other medical issues later that month.

Before the meeting, Edward J. Markey, congressman and chairman of the Energy and Environment Subcommittee of the House Committee on Energy and Commerce, wrote a letter to the chairman of the NRC expressing concern over public exposure to radiation due to patients being treated with radioiodine on an outpatient basis. Markey claimed that the public has been “unwittingly exposed to radiation from patients who are discharged after being treated with radioisotopes,” and blamed weak NRC regulations for the exposure.

Richard T. Kloos

“There is no good evidence of the public being harmed by exposure to people who were treated with radioiodine,” Richard T. Kloos, MD, professor at Ohio State University, divisions of endocrinology and nuclear medicine, said in an interview. “That being said, while we don’t have any evidence of harm, we should still try to keep any risk that may exist as low as is achievable.”

Established treatment

Radioiodine has been used for more than 50 years to treat a variety of thyroid diseases, including thyroid cancer, and has been found to have relatively few undesirable effects, according to AACE. Typically, patients with thyroid cancer undergo surgery followed by treatment with radioiodine. Patients receive the treatment by mouth and during the first few days after the outpatient procedure the radioiodine will leave the body through saliva, sweat, urine, tears, vaginal secretions, semen and feces.

Although originally an inpatient procedure, in 1997, the NRC revised its recommendations about patient release after radioiodine treatment, allowing patients to be released provided the dose to any other individual exposed to the patient did not exceed 5 mSv. This resulted in most patients undergoing radioiodine treatment in an outpatient setting, an approach that, according to the joint statement, “enhances patient satisfaction and is the current standard of medical practice.”

Physicians are supposed to educate patients about appropriate behavior after treatment and issue recommendations about interacting with others to minimize risk (see sidebar).

A study by Grigsby and colleagues published in 2000 in the Journal of the American Medical Association supported this recommendation. Results indicated that for household members of 30 patients who underwent radioiodine treatment, the dose of radiation exposure to any member was “well below” the 5 mSv limit recommended by the NRC.

“When people are sent home, they fill out a large group of papers that explain all of the things that they need to avoid,” said Ernest Mazzaferri, MD, professor of medicine in the division of endocrinology, diabetes and metabolism at the University of Florida, Gainesville.

Ernest Mazzaferri

Close and prolonged contact with others and exposure to bodily fluids are the biggest concerns.

“We don’t want people kissing or sharing a drink,” said Kloos, who is also secretary and chief operating officer of the ATA. “People should stay at least an arm’s length away for a few days or up to a week.”

The greatest precautions are taken to protect children and young teenagers who physicians theorize may be at the highest risk for harm due to exposure, Kloos said. However, even that risk is theoretical, with little to no data to support it, he added.

Evidence needed

“The problem is, of course, that you can give people advice, but not everyone follows it,” Mazzaferri said. “We are all beginning to recognize that may be a bigger problem than we thought.”

However, Kloos did not classify radiation exposure due to radioiodine as a public health concern.

“I wouldn’t put it in the top list of major problems facing our population,” he said. “Radiation is a scary word that grabs public attention.”

In addition, returning to the days of inpatient radioiodine treatment would come with a larger set of issues, Kloos said. Among them are increases in health care costs and increased waiting times for treatment due to a shortage of hospital rooms equipped with the proper precautions, such as lead lining.

“However, there is enough of an issue here that the various major organizations are, as we speak, trying to put together something that would put more safety features in place,” Mazzaferri said.

The ATA recently assembled a document to help make recommendations for outpatient treatment with radioiodine more uniform across hospitals and eliminate any confusion that may exist, according to Kloos.

“I found in the media coverage of this issue that people felt they were not adequately informed or told the correct way to handle this situation,” Kloos said. “I find that sad.”

However, he added, in most cases, when competent health care providers who provide this treatment know and instruct on published recommendations, most people are willing and able to follow them.

“If we make people think that treatment with radioiodine is so bad that nobody wants to take it, the primary treatment for thyroid cancer will be surgery alone,” Mazzaferri said. “Unfortunately, you need surgery and radioiodine to get full destruction of this disease.

“Exposure may be found to be a problem, but it is not so great a problem that we should quit using this effective treatment,” he said. – by Leah Lawrence

For more information:

• AACE. 2004. ”Radioiodine Therapy: Information for Patients.”
• Grigsby PW. JAMA. 2000;283:2272-2274.
• Joint statement on radioactive precautions following radioactive iodine therapy. Oct. 20, 1010.