The frequency of vomiting after outpatient I-131 therapy (tx) in patients (pts) with well-differentiated thyroid cancer (WDTC)

Objectives Many controversies exist regarding I-131 tx performed as either an inpt or outpt. One controversy involves the potential that a pt may vomit shortly after administration of I-131 when not in the hospital. The objective of this study is to evaluate the frequency, severity, time of onset, and duration of vomiting after outpt I-131 tx in pts who have WDTC.

Methods A survey involving I-131 tx was e-mailed to associates of the Thyroid Cancer Survivors’ Association and available to anyone on its website. Responses of pts with WDTC who had a least one outpt I-131 tx and were tx’ed in the United States or its territories (US) were tabulated for the aforementioned questions. Only responses by the pt for their most recent I-131 outpt tx were included.

Results Out of 15,000 surveys sent out, 1299 pts responded. Of these, 831 had at least one outpt I-131 tx in the US. Of 801 responses, 81(10%) had vomiting. Of 75 responses, vomiting was categorized as mild 19(25%), moderate 32(42%), and severe 24(32%). Of 73 responses, the times of vomiting after I-131 tx were <30min 3(4%), 0<1hr 0(0%), 1<2hrs 5(6.8%), 2<3hrs 5(6.85), 3<4hrs 9(12%), 4<5hrs 7(9.5%), 5<6hrs 6(8%), 6<12 hr 3(4%), 12<18 hr 3(4%), 18<24 hr 11(15%), 24<48 hr 4(5%), 48<72 hr 6(8%), >72 hr 11(15%). During the first 3 & 4 hrs after administration of I-131, vomiting occurred in 1.8% & 3%, respectively. The duration of vomiting for 73 responders was 0<1hr 17(23%), 1<2hr 8(10.9%), 2<3hr 10(13.7%), 3<4hr 4(5.4%), 4<5hr 0(0%), 5<6hr 0(0%), 6<12hr 5(7%), 12<18hr 3(4%), 18<24hr 5(7%), 24<48hr 5(7%), 48<72hr 7(9%), >72hr 9(12%).

Conclusions Although the frequency of vomiting outside of the hospital in the first 3 to 4 hours is low in the responders to this survey, we believe that because the patient is being administered I-131 in the range of 33 to 200 mCi or more, a period of observation in the tx facility of at least 3 hrs is warranted