Hemodialysis-associated radioactive waste management in [¹³¹I]I and [¹⁷⁷Lu]Lu radionuclide therapy

Radionuclide therapy, such as with iodine-131 or lutetium-177-labeled substances, is used to treat thyroid cancer and neuroendocrine tumors. Due to the incorporated radioactivity, patients must remain hospitalized until radiation levels are deemed safe, according to national regulations. This is particularly problematic for patients who require hemodialysis (HD). While contamination of dialysis waste after radionuclide therapy is generally well recognized, a critical gap remains regarding its duration and extent. This poses risks for patient management and outpatient staff.

This study aims to demonstrate the problems with classifying residual waste and provides arguments for appropriate regulation. It evaluates if the radioactivity of the dialysate and residuals at discharge, based on whole-body measurements, complies with relevant limits. If not, the waste is classified as radioactive and treated accordingly.

We studied four patients treated by radionuclide therapy who required dialysis: three received [¹³¹I]I for thyroid disease and one [¹⁷⁷Lu]Lu-DOTATATE for neuroendocrine neoplasia. Dialysis was performed in the nuclear medicine ward, and patients were discharged once the local dose rate limits were met. Subsequent dialysis sessions were conducted in a radiation protection area until the activity concentration in the dialysate dropped below the specific limit.

Patient 1 ([¹³¹I]I, thyroid cancer) showed the highest extraction rate and was discharged after 9 days, requiring nine additional dialysis sessions over 21 days. Patients 2 and 3 ([¹³¹I]I, benign thyroid disease) were discharged after 8 and 4 days, with dialysis continued for 31 and 18 days under supervision, respectively. Patient 4 ([¹⁷⁷Lu]Lu-DOTATATE) lost 4.9% of the total body radioactivity per dialysis session and was discharged after 9 days; supervised dialysis continued for 17 days.

This study highlights the need for refined monitoring and the limitations of standard discharge strategies for patients requiring dialysis during radionuclide therapy. Even if dose limits are met, dialysate and residuals may still require regulated handling and storage.