Qualitative and quantitative impact of lithium carbonate pretreatment on the effective 131-I half-life in radioiodine therapy for hyperthyroidism: results from a retrospective study

Abstract

Objective: The aim of this study is to evaluate the impact of lithium carbonate pretreatment on the effective 131I half-life (EHL) in radioiodine therapy (RIT) for hyperthyroidism. Design: This analysis of 225 patients diagnosed as hyperthyroidism at our institution between February 2015 and September 2021 was retrospectively registered (registration number: 2024-KY-0016, date: Jan 4, 2024). Methods: The basic clinical and laboratory examination data before and after lithium carbonate pretreatment was recorded. Whether the EHL was extended by ≥ 0.5 days has been established as the grouping basis. The differences of the clinical factors between the two groups were analyzed, and possible factors predicting whether longer EHL could be achieved was carried out using logistic regression analyses. Results and conclusions: The result showed that a 7-day lithium carbonate pretreatment could increase radioactive iodine uptake rate (RAIU) at 24 h (by 9.93%), EHL (by 8.17%), and decrease FT3 (by 20.85%), FT4 (by 11.93%) levels in hyperthyroidism patients in this retrospective study. It is indicated that not all patients with hyperthyroidism could achieve longer EHL after using lithium carbonate. Young female with positive TRAb, positive TgAb, low blood concentration of TPOAb, and/or short baseline EHL is more likely to achieve longer EHL after a short-term lithium carbonate administration.