Abstract
The authors of the recently published “Radiation Safety in the Treatment of Patients with Thyroid Diseases by Radioiodine (131I): Practice Recommendations of the American Thyroid Association” (1) are to be commended for creating a document that reflects the result of countless hours of literature review, survey compilation, discussion, and compromise. This study has systematically applied techniques to achieve as low as reasonably achievable (ALARA) exposure to radiation, and this represents a significant step forward in the protection of those coming in contact with individuals treated with 131I. It effectively communicates newer approaches to assessing the likely maximum dose to another person (usually family) that are not only based on total administered doses but also estimates of clearance and retention. For example, an individual with Graves' disease with high radioactive iodine uptake who received 10 millicurie (mCi) of 131I may expose others to more radiation than someone with thyroid cancer post–total thyroidectomy, stimulated with rhTSH and ablated with 100 mCi. We have already modified our institution's protocols by adapting some of the committee's recommendations.
However, we would like to share our concerns about some of the committee's recommendations regarding the following.
In regard to the section titled “Post-therapy living situations,” the recommendation about sleeping in separate beds, the committee should consider the dynamic clearance of the 131I as predicted by the expected pharmacokinetics of 131I. For example, the amount of radioiodine delivered to and retained in the thyroid gland of a patient with Graves' disease who receives 10 mCi is often greater than the radiation exposure of someone with a multinodular goiter who is either euthyroid or only mildly hyperthyroid receiving 30 mCi. Yet, the former patient would be advised to sleep alone for 3 days, while the latter patient would be told to do so for 11 days.
The section entitled “Personal hygiene” contains instructions on the disposal of radioactive trash that cannot be flushed or washed in a routine fashion which require several considerations. First of all, just how much contamination will there be? Highly conscientious, environmentally aware, independently living people are unlikely to generate much radioactive trash. On the other hand, a debilitated, dependent patient, who wears incontinence diapers, is quite likely to produce a significant amount of contamination. Recommendations should, therefore, be based on likely levels of contamination. For example, when considering the use of disposable versus washable utensils, we recommend using washable utensils—as opposed to disposable ones. We instruct patients to wash them separately from the family dishes whenever possible. This minimizes the amount of material that must be stored. When counseling patients about transporting radioactive trash, the recommendation states, “Bring your specified trash bag back to the treatment facility.” We feel that it is not feasible for many urban dwellers who are dependent on public transportation, which should not be used for this purpose, to comply with this recommendation. Further, in regard to the home storage of radioactive trash, it is recommended that, “After 80 days the bag may be removed as other trash bags.” We believe that holding biohazard trash for 80 days poses a hygienic risk and storage challenge for those living in small apartments in multi-unit dwellings. Seeking alternative storage options may force them to compromise their right to privacy and expose others to unnecessary radiation. We recommend landfill disposal after a shorter period for continent patients, such as 4 weeks depending on the sensitivity of local landfill detectors. Incontinent patients should be treated as inpatients. Willegaignon et al.'s (2) experience in Brazil indicates that patient home waste contamination levels were a third of the International Atomic Energy Agency (IAEA) concentration limit for release criteria. We propose that our professional societies request that the Nuclear Regulatory Commission (NRC) adopt IAEA limits as reasonable alert levels for waste site monitors.
Driving an automobile while potentially impaired by the effects of hypothyroidism has led us to carefully consider our recommendations to patients undergoing thyroid hormone withdrawal procedures. We routinely instruct patients who are overtly hypothyroid not to drive. Consider, for example, the case of a school bus driver with severe hypothyroidism who caused a fatal collision, cited by Rosenthal (3). First and foremost this tragedy could have been prevented by not allowing an impaired driver to perform his duties. It is unclear who would be held responsible, including the physician, if school authorities were not notified that an overtly hypothyroid individual would be driving a school bus. Case law seems to indicate that physicians who fail to warn their hypothyroid patients against driving are negligent. Also, that physicians who fail to warn third parties about an impaired hypothyroid patient's driving, that places the public in peril, may be negligent (3). Anticipating how well a euthyroid patient will drive when he or she is rendered overtly hypothyroid is not possible. Additionally, assessing the ability to drive safely, when the patient is overtly hypothyroid, is neither feasible nor objective as suggested in the section on “Post-therapy travel.” We therefore recommend that patients who are overtly hypothyroid be transported by a family member to their appointments.
In summary, the newly published recommendations of the American Thyroid Association regarding radiation safety for those being treated with radioactive iodine provide clinically understandable guidance to assure the safety of family and the general public. We trust that the authors will address our concerns and consider incorporating or referring to our practice in future versions of these practice recommendations.