‘LT3-treatment’ protocol of short-term hypothyroidism induction in patients with differentiated thyroid carcinoma: a safer strategy with lower risk of laboratory abnormalities compared to ‘no treatment’ protocol

Aims: The utilization of levotriiodothyronine (LT3) during hypothyroidism induction remains relatively unexplored in patients with differentiated thyroid carcinoma (DTC). This study aimed to compare laboratory findings for ‘non-treated’ versus ‘LT3 treated’ protocols of short-term hypothyroidism induction in patients with DTC. Methods: A total of 130 patients with DTC who had thyroxine withdrawal to induce hypothyroid state prior to RAI ablation after initial surgery were included in this retrospective study. Patients were divided into two groups based on characteristics of thyroxine withdrawal period including those followed without treatment during the entire hypothyroidism induction period (non-treated group, n=67) and those followed with administration and then discontinuation of LT3 for the last 2 weeks of induction (LT3-treated group, n=63). Results: Not-treated vs. LT3-treated patients had significantly lower post-induction platelet counts (p=0.001) and smaller increase in platelet counts from baseline (p=0.005), higher increase from baseline total cholesterol (p=0.025), greater decrease in Ca from baseline (p=0.032), greater increase from baseline creatinine (p=0.041) and higher post-induction TSH (p=0.021). Conclusion: In conclusion, ‘LT3 treatment strategy’ seems to have several advantages over ‘no treatment strategy’ during short-term hypothyroidism induction in terms of reducing the risk of laboratory abnormalities such as milder raise in serum creatinine, calcium and total cholesterol levels, while ensuring the effective stimulation of endogenous TSH levels sufficient for radioiodine therapy.