Abstract Title:

Alterations in Coagulation and Fibrinolysis after Levothyroxine Exposure in Healthy Volunteers: A Controlled Randomized Crossover Study.

Abstract Source:

J Thromb Haemost. 2011 Jul 5. Epub 2011 Jul 5. PMID: 21729238

Abstract Author(s):

B van Zaane, A Squizzato, J Debeij, O M Dekkers, J C M Meijers, A P van Zanten, H R Büller, V E A Gerdes, S C Cannegieter, D P M Brandjes

Article Affiliation:

Department of Internal Medicine, Slotervaart Hospital, Amsterdam, the Netherlands Department of Vascular Medicine, Academic Medical Center, Amsterdam,


Background: Several hemostatic abnormalities have been reported in hyperthyroidism, but the overall effect of thyroid hormone excess on coagulation and fibrinolysis is unclear. Objective: Our aim was to assess whether the use of supraphysiological doses of levothyroxine leads to coagulation activation and inhibition of fibrinolysis. Patients/Methods: Healthy volunteers were randomized to receive levothyroxine or no medication for 14 days with a wash-out period of at least 28 days in a crossover design. To study the effects of different degrees of thyroid hormone excess, 16 participants received levothyroxine in a dose of 0.3 mg/day, and 12 received levothyroxine 0.45 or 0.6 mg/day depending on body weight. Several variables of coagulation and fibrinolysis were measured. Results: Levels of von Willebrand factor activity (VWF:RiCo) and antigen (VWF:Ag), factor (F) VIII, plasminogen activator inhibitor-1 (PAI-1) and clot-lysis time were slightly higher after levothyroxine 0.3 mg/day than after the control situation, but only levels of VWF showed a significant increase from baseline. After levothyroxine 0.45 or 0.6 mg/day, levels of fibrinogen increased by 17%, VWF activity by 24%, VWF antigen by 26%, factor VIII by 19%, factor IX by 14%, factor X by 7%, PAI-1 by 116%, clot-lysis time by 14%, and activated partial thromboplastin time decreased by 3%; all significant changes compared to the control situation. We did not observe clear evidence of coagulation activation. Conclusions: Our data suggest that thyroid hormone excess increases coagulation factor levels and inhibits fibrinolysis in a dose-dependent fashion. This implies an increased risk of venous thrombosis during hyperthyroidism.

Study Type : Human Study

Print Options

Key Research Topics

Sayer Ji
Founder of GreenMedInfo.com

Subscribe to our informative Newsletter & get Nature's Evidence-Based Pharmacy

Our newsletter serves 500,000 with essential news, research & healthy tips, daily.

Download Now

500+ pages of Natural Medicine Alternatives and Information.

This website is for information purposes only. By providing the information contained herein we are not diagnosing, treating, curing, mitigating, or preventing any type of disease or medical condition. Before beginning any type of natural, integrative or conventional treatment regimen, it is advisable to seek the advice of a licensed healthcare professional.

© Copyright 2008-2022 GreenMedInfo.com, Journal Articles copyright of original owners, MeSH copyright NLM.