S-Space College of Medicine/School of Medicine (의과대학/대학원) Laboratory Medicine (검사의학전공) Journal Papers (저널논문_검사의학전공)
Endothelial Function is Not Changed during Short-Term Withdrawal of Thyroxine in Patients with Differentiated Thyroid Cancer and Low Cardiovascular Risk
- Chang, Hyuk-Jae; Kim, Kyung Won; Lim, Soo; Choi, Sung Hee; Choi, Dong Joo; Cho, Bo Youn; Park, Young Joo; Jang, Hak C.; Park, Do Joon; Park, Kyoung Un
- Issue Date
- YONSEI UNIV COLLEGE MEDICINE
- YONSEI MEDICAL JOURNAL; Vol.51 4; 492-498
- Short-term hypothyroidism; endothelial dysfunction; radioactive iodine; flow-mediated vasodilatation; thyroid cancer
- Purpose: The incidence of differentiated thyroid cancer is increasing in young adults and females in Korea. Some of them experience short-term hypothyroidism in preparation for radioiodine (RAI) therapy, which can have a deleterious effect on the cardiovascular system. However, it is not clear if short-term hypothyroidism induces endothelial dysfunction in patients with low cardiovascular risk. Therefore, the aim of this study was to investigate whether short-term hypothyroidism is associated with endothelial dysfunction in patients with low cardiovascular risk. Materials and Methods: To evaluate the effect of short-term hypothyroidism on endothelial function in this group, we recruited fifteen female patients with low cardiovascular risk. We analyzed clinical, biochemical, and cardiovascular parameters at four time points: the last day on levothyroxine (LT4) at their usual thyroid-stimulating hormone (TSH)-suppressive doses (P1), 7 days (P2) & 4 weeks (P3) after withdrawal of LT4, and 8 weeks (P4) after replacement of the previous dose of LT4. A high resolution ultrasound was used to measure brachial artery diameter at rest, after reactive hyperemia, and after sublingual nitroglycerin. Results: During short-term hypothyroidism (P3), serum concentrations of total cholesterol and low-density lipoprotein (LDL)-cholesterol were increased (p < 0.001 for each period). In spite of having worsened lipid states, serum high sensitivity C-reactive protein or flow-mediated vasodilatation, which is one of the surrogate markers of the endothelial function, did not change during short-term hypothyroidism. Conclusion: Short-term hypothyroidism induced worsening of metabolic parameters, but not enough to induce the endothelial dysfunction in patients with low cardiovascular risk.