Purpose: We describe a murine model to evaluate variations of a published multicenter thyroid blocking protocol described for 131I antibody therapy, using doses of blocking agents proportional to those used in man. Variables described for 131I antibody therapy, using doses of blocking agents proportional to those used in man. Variables Materials and Methods: Whole-body activity measurements were performed 0, 24, 48 and 72 hours following 131I-NaI administration in control and thyroid-blocked mice. Retained whole-body activity was calculated as a percentage of the injected dose (%ID), primarily reflecting radioiodine sequestered in the thyroid gland. In blocked groups, SSKI was begun one or 7 days preceding 131I-NaI therapy, and was supplemented in one half of the cases with KClO4 from time of therapy. Results: In control mice, %ID was 11.23 ± 1.47%, 10.15 ± 1.11% and 9.29 ± 1.50% at 24, 48 and 72 hrs respectively. %IDs of blocked groups were markedly lower than controls (p=.0001). In the one day SSKI pretreatment group, %ID was reduced from 1.73 ± 0.58, 1.42 ± 0.45 and 1.20 ± 0.38 at 24, 48 and 72 hours to 0.49 ± 0.08, 0.50 ± 0.07 and 0.44 ± 0.06 with addition of supplemental KClO4. In the 7 day SSKI pretreatment group, %ID was reduced from 1.87 ± 0.73, 1.48 ± 0.49 and 1.36 ± 0.57 at 24, 48 and 72 hours to 0.60 ± 0.36, 0.45 ± 0.13 and 0.41 ± 0.14 with addition of supplemental KClO4. %IDs in the 7 day pretreatment animals were not statistically different from those in the one day pretreatment groups (all p>>0.05). Conclusion: SSKI reduces retention of radioiodide approximately six-fold whereas supplemental KClO4 enhances thyroid blocking an additional three-fold. Seven day SSKI pretreatment appears no more effective than one day pretreatment.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Cancer Research