Radioactive Iodine: Recommendations for Public, Patients

Neil Osterweil

April 13, 2011

April 13, 2011 — New safety recommendations related to the use of radioactive iodine (I131) in the outpatient treatment of hyperthyroidism and thyroid cancer have been issued by American Thyroid Association.

The recommendations are published in the April issue of Thyroid.

The goal of the recommendations is to limit the radiation exposure of family members, caregivers, and the general public from patients treated with radionuclides, write lead author James C. Sisson, MD, professor emeritus at the University of Michigan in Ann Arbor, and colleagues.

"The task force recognized that several of the precautions traditionally thought to be necessary offered little benefit or protection from radiation exposure, whereas others that were often overlooked served to reduce exposure," they write.

The recommendations cover practical matters related to patients who return to the world in a state of radioactivity. Topics include travel; precautions at home, work, and school; personal hygiene; and pregnancy and breastfeeding.

These are not evidence-based recommendations; instead, they draw on the expertise and experience of specialists in nuclear medicine, radiation safety, medical physics, endocrinology, and endocrine surgery to help clinicians and patients understand which safety precautions are necessary and which are superfluous, and help ensure that radiation exposures are held to a standard that is "as low as reasonably achievable."

The panelists reviewed Nuclear Regulatory Commission (NRC) regulations regarding maximum allowable exposure to others of patients released after nuclear medicine procedures, and sought input on the practices and safeguards in place at the institutions where the panel members work.

Snapshot of Practice

As part of the process, the panelists polled 311 colleagues at various institutions about their safety precautions and patient instructions, and found that "even within some institutions, there was disparity in radiation safety instructions provided by the referring physician, the Nuclear Medicine Department, and/or the [radiation safety officer]."

In a commentary published in the February issue of Thyroid, Richard T. Kloos, MD, from the division of endocrinology and nuclear medicine at the Ohio State University in Columbus, noted that the survey revealed several unsettling findings.

"It is surprising that some respondents accepted written or verbal patient statements of being not pregnant, and quite concerning that one respondent indicated that they 'never' screen for pregnancy," he writes. "Also concerning was that 5% to 11% of respondents apparently had no threshold to advise patients regarding certain practices to follow in the first 24 hours after treatment. These desirable practices include avoiding children 2 to 10 years of age, maintaining a specific time and/or distance from other people, and avoiding public transportation."

The survey results highlight the need for clear, consistent, and practical recommendations for healthcare providers and patients, Dr. Kloos writes.

Summary of Recommendations

Radiation safety officer: All treatments should be provided by a clinician trained in the administration of radiopharmaceuticals, under safety precautions/protocols determined by the radiation safety officer. The radiation safety officer should also develop patient-specific precautions, taking into account the predicted retained radioactivity in each patient.

Pregnancy/reproduction: Women from the age of menarche to 2 years after menopause should be tested for pregnancy, and should be informed that pregnancy is a contraindication to I131 therapy. Women should avoid becoming pregnant for 6 months after treatment to allow for the normalization of thyroid levels. Men should be advised that fathering a child within 3 months of radiation exposure has not been associated with an increase in congenital abnormalities or fetal. They should be advised, however, that full fertility may not return for 1 year, and that they should not attempt to produce a pregnancy until at least 3 months after the completion of I131 therapy.

Breastfeeding: Breastfeeding should be discontinued because of the risk to the infant related to exposure during lactation.

Dose rate calculations to determine distance: When exposure from a treated patient at 1 meter (3.2 feet) exceeds the NRC-defined regulatory limit of less than 7 millirem/hour, people should remain at least 6 feet (1.8 meter) away, although adults can be within 1 meter of the patient for brief periods, "preferably only for minutes." Patients should drive alone or, when riding in a car, stay as far away from other occupants as possible.

Travel through ports of entry: For 4 months after therapy, patients crossing borders (via airports, tunnels, or bridges) should carry a form specifying the date of treatment, radionuclide used, and provider contact information.

Posttherapy accommodations: Patients should not stay in hotels, should avoid public transportation, and should avoid being in close proximity to others.

Personal hygiene: Patients should use special precautions, especially during the first 48 hours, to minimize the possibility of exposing others to urine, stool, saliva, blood or bodily fluids, perspiration, or vomit. Specialized leak-proof waste disposal bags should be made available to the patient during the restricted period.

The recommendations and survey were supported by the American Thyroid Association. The authors have disclosed no relevant financial relationships. Dr. Kloos is secretary and chief operating office of the American Thyroid Association.

Thyroid. 2011;21:97-99, 335-346. Commentary, Recommendations

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