ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2008) 16 P794

Decreased fibrinolytic activity due to levothyroxine suppression therapy for benign thyroid nodules

Tevfik Demir, Baris Akinci, Abdurrahman Comlekci, Oguzhan Karaoglu, Serkan Yener, Mehmet Ali Ozcan, Faize Yuksel, Mustafa Secil & Sena Yesil


Dokuz Eylul University, Izmir, Turkey.


Thyroid dysfunction is associated with altered levels of several coagulation factors. The aim of this study is to investigate the effect of levothyroxine suppression therapy for benign thyroid nodules on coagulation system.

Thirty-six patients with benign thyroid nodules, who were applicant for levothyroxine suppression therapy, were included in the study. Thirty patients completed 1 year follow-up period. Levothyroxine was given to maintain TSH level between 0.1 and 0.35 mIU/l. Samples were collected before and after therapy.

No significant decrease in diameters and volumes of 128 thyroid nodules were observed after one year levothyroxine suppression (P>0.05). No alteration was found in plasma tPA ve tfPI levels after therapy (P>0.05). However, plasma fibrinogen (P<0.001), d-dimer (P<0.001), vWF (P=0.025), and PAI-1 antigen levels (P=0.032) increased after levothyroxine suppression. On the other hand, plasma TAFI antigen levels decreased significantly (P=0.005).

Our results suggest a decrease in fibrinolytic activity after levothyroxine suppression therapy for benign thyroid nodules. The decrease in TAFI antigen levels may be due to activation of TAFI pathway.

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