ORIGINAL ARTICLES   

Minerva Endocrinologica 2006 June;31(2):173-8

Copyright © 2006 EDIZIONI MINERVA MEDICA

language: English

Effects of thyroxine withdrawal in biochemical parameters and cardiac function and structure in patients with differentiated thyroid cancer

Chrisoulidou A. ¹, Pazaitou-Panayiotou K. ¹, Kaprara A. ¹, Platoyiannis D. ², Lafaras C. ², Boudina M. ¹, Georgiou E. ¹, Drimonitis A. ¹, Bischiniotis T. ², Vainas I. ¹

¹ Department of Endocrinology and Endocrine Oncology Theagenio Cancer Hospital, Thessaloniki, Greece 2 Department of Cardiology, Theagenio Cancer Hospital, Thessaloniki, Greece

Aim. Patients with differentiated thyroid carcinoma (DTC) are closely monitored during the first decade after diagnosis. At intervals of 1-2 years withdrawal of suppressive doses of T4 is recommended in order to check thyroglobulin (Tg) levels under increased TSH. T4 therapy is usually withdrawn for 5 weeks (during the first 3 weeks patients receive treatment with T3 instead of T4, and the last 2 weeks stop all medication). There are a few reported studies looking into the effects of T4 withdrawal in athyreotic patients in terms of biochemical parameters and ultrasound indices. We studied patients with DTC at two time points: during suppressive T4 treatment and at the end of the T4 withdrawal protocol in order to identify acute changes that become apparent after 5 weeks of treatment modification.
Methods. Hormonal and biochemical parameters were measured as well as ultrasound indices of cardiac function and structure.
Results. Statistically significant increases were found in total cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) cholesterol and triglycerides with T4 withdrawal. Creatine phosphokinase showed a striking increase with treatment withdrawal. In addition, liver enzymes, total protein and albumin concentrations increased. Creatinine levels increased significantly and sodium decreased on stopping T4 treatment. The ultrasound indices of cardiac function and structure did not show significant changes.
Conclusion. Acute hypothyroidism following T4 withdrawal in DTC patients leads to important biochemical changes without significant alterations in cardiac function and structure. These changes may adversely affect patients, especially older patients or those with other chronic diseases.