Effects of thyroid hormone withdrawal on metabolic and cardiovascular parameters during radioactive iodine therapy in differentiated thyroid cancer. (February 2017)

• Record Type: Journal Article
• Authors: An, Jee Hyun; Song, Kee-Ho; Kim, Dong-Lim; Kim, Suk Kyeong
• Is Part Of: Journal of international medical research. Volume 45:Number 1(2017)
• Page Start: 38
• Page End: 50
• Publication Date: 2017-02
• Subjects: Hypothyroidism -- atherosclerosis -- metabolic syndrome -- thyroid hormone withdrawal -- thyroid cancer; Medicine -- Periodicals; Pharmacology -- Periodicals; 610.5
• DOI: 10.1177/0300060516664242
• Languages: English
• ISSNs: 0300-0605

Abstract

Objective: To investigate the cardiometabolic effects of a severe hypothyroid state induced by withdrawal of thyroid hormone replacement before radioactive iodine therapy. Methods: Patients with thyroid cancer who were scheduled to receive radioactive iodine ablation were enrolled. Cardiometabolic parameters were measured using blood samples taken immediately before levothyroxine withdrawal, 4 weeks following withdrawal (on radiotherapy day), and 4 weeks following reinstitution of levothyroxine. Results: Out of 48 patients (age 49.4 ± 10.5 years; 77.1% [37/48] female), the severe hypothyroid state induced by levothyroxine withdrawal significantly aggravated the majority of lipid parameters, particularly in patients with a greater number of metabolic syndrome components. Fasting plasma glucose levels and homeostatic model assessment values for insulin resistance and β-cell function significantly decreased following levothyroxine withdrawal. Serum high-sensitivity C-reactive protein, fibrinogen and cystatin C levels significantly decreased, and homocysteine levels increased during the severe hypothyroid state. All of these changes were reversed by levothyroxine reinstitution. Conclusions: Severe hypothyroid state induced pronounced changes in cardiometabolic parameters. Further studies should identify the long-term effects of changes in these parameters on cardiovascular morbidity and mortality in relation to thyroid disease.