Endocrine Abstracts

Introduction: The degree of dyslipidemia caused by iatrogenic hypothyroidism is not clear in DTC. Therefore, we investigated the average of lipid profile change caused by LT₄ withdrawal in the follow-up of DTC.

Method: We enrolled 84 DTC patients who underwent high-dose RAI therapy for the treatment of recurred or remnant DTC and we measured serum levels of total cholesterol, triglyceride, LDL, and HDL and then analyzed changes in them according to the LT₄ withdrawal. Moreover, we also compared the results of TSH-stimulated Tg with anti-Tg antibody and I-131 scan with sole radiologic evaluation including neck sonography.

Results: The mean degree of the increase following LT₄ withdrawal in serum levels of total cholesterol, triglyceride and LDL was 70.51±11.4, 87.9±23.3 and 44.4±9.4 mg/dl, respectively. Of the 84 patients, 29 were suspected of having tumor recurrence or remnant and they underwent repeated high-dose RAI or re-operation. However, there were no changes in the management of other 65 patients because their levels of TSH-stimulated Tg was below 1 ng/ml following LT₄ withdrawal and they had no remnant or recurred disease on imaging studies. Furthermore, despite a lack of the data about T₄ withdrawal Tg/anti-Tg anti-body, all the remnant DTCs could be detected solely by radiological assessments in the re-treated 29 cases.

Conclusion: Our results re-confirmed that iatrogenic hypothyroidism was associated with a significant increase in atherogenic lipid levels and this study showed the mean degree of the derangement of lipid profiles by T₄ withdrawal in patients with DTC at first. In addition, it was also shown that TSH stimulated Tg could not show the more efficient detection in the DTC recurrence compared to sole image modalities even though in the high risk patients of DTC recurrence or remnant.