Metabolic irradiation of differentiated thyroid cancers and periodic hemodialysis

The association of a terminal renal insufficiency with a thyroid well-differentiated cancer is a rare contingency which complicates the 131I therapy in these patients. A women 56 years old has been treated by administration of 3700 MBq (100 mCi) of 131I for a thyroid well-differentiated cancer after a complete thyroidectomy (with a 131I fixation rate on 24 h < 1%). Due to a terminal renal insufficiency 3 weekly hemodialysis sessions were necessary. The hemo-dialyses were achieved at the 3. and 5. day after the iodine administration. The dose rate at 1 meter during the first three days remained constant at 90 μGy/h. The circulatory activity amounted up to 1.8% of the injected activity. The post-dosage whole-body scintigraphy evidenced an iodo-fixation cervical relic with a iodine biological half-time of 77.66 h, while the delivered dose amounted up to 250 mGy. The first dialysis at the 3D has reduced the dose rate at 1 meter to 60% and the circulatory activity to 73%. The cumulative activity over 5 days at the level of tumoral residue is only slightly modified by the dialyses. The dose rate at 1 meter of the dialysis appliance after washing was lower than 10 μGy/h. No significant radioactivity was detected in the disposable material used in dialysis. In conclusion, the administration of 131I does not result in any contamination of the materials of dialysis. The biological half-time of iodine at the level of thyroid tumor parenchyma is short. Consequently, this treatment should be reserved for the cases of detectable masses with 'tracing' doses of 131I, but higher 'therapeutic' activities of 131I are necessary. To reduce the dose delivered in critical organs the hemodialysis could be carried out after the 24. hour