The effect of hormone replacement treatment on thrombin-activatable fibrinolysis inhibitor activity levels in patients with Hashimoto thyroiditis

Abstract

Background: Hypothyroid patients have increased risk of cardiovascular diseases, and several mechanisms have been considered responsible in these patients. Although, a few studies demonstrated fibrinolytic system changes in hypothyroid patients, there is no study demonstrating TAFI activity in hypothyroid Hashimoto's thyroiditis patients. The aim of this study was to evaluate TAFI activity status and the effect of L thyroxin hormone replacement treatment on fibrinolytic system in this patient group. Methods: Thirty patients with hypothyroid Hashimoto thyroiditis (all were female and the mean age was 44.3±14.6 years, ranging between 17-68 years) were enrolled to study. Their TSH levels were high (27.2±5.2 mU/L) and Free T3 and Free T4 hormone levels were below than normal. In this study, euthyroid 20 healthy volunteers (mean age 32.5±4.9 years, range 26-42 years) were adopted. L-thyroxin treatment before and after TAFI activity levels were measured in patients. Results: In the control group, TAFI activity levels were 9.6±0.4 μg/mL. In patients with L-thyroxin before and after treatment there were high levels of TAFI activity value of 14.2±0.9 and 12.9±0.8 μg/mL, respectively. In the patient group, after L-thyroxin treatment TAFI activity levels were decreased but they were not statistically significant (p=0.187). When compared to the control group, high levels of TAFI activity were observed in the patient group (p<0.0001). Conclusion: Our data demonstrated that in Hashimoto thyroiditis, patients have high levels of TAFI activity compared to controls. A high level of TAFI activity suggests fibrinolytic deficit or thrombotic tendency in hypothyroid patients and this deficit is persistent after L-thyroxine replacement. © 2009 The Japanese Society of Internal Medicine.