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Relationship between thyroid hormones and plasma D-dimer levels
R Chadarevian1, E Bruckert, A Ankri
1Service d'Endocrinologie-Métabolisme, Hôpital Pitié Salpétrière, Paris, France.
Insights
Low free thyroxine (fT4) levels are linked to a hypercoagulable state in hyperlipidemic patients. This suggests fT4 plays a role in regulating blood clotting and hemostasis in this population.
Area of Science:
- Endocrinology
- Hematology
- Cardiovascular Disease
Background:
- Hyperlipidemia is a risk factor for coronary heart disease.
- Thyroid disorders frequently coexist with hyperlipidemia and are linked to hemostatic abnormalities.
Purpose of the Study:
- To investigate the relationship between free thyroxine (fT4) levels and key hemostatic parameters in hyperlipidemic patients.
- To determine if fT4 influences coagulation factors like Factor VII (FVIIc), Factor VIII (FVIIIc), D-Dimer (DDI), and Plasminogen Activator Inhibitor type 1 (PAI-1).
Main Methods:
- Analysis of 472 hyperlipidemic patients, including 40 with primary hypothyroidism.
- Correlation analysis between fT4 levels and FVIIc, FVIIIc, DDI, and PAI-1.
- Multivariate regression analysis to assess independence from other factors like age, BMI, gender, and total cholesterol.
Main Results:
- A significant negative correlation was observed between fT4 and D-Dimer (DDI) in the overall population (p = 0.0001, r = -0.21).
- This negative correlation persisted after excluding patients with subnormal fT4 levels (p = 0.0007, r = -0.17).
- The association between fT4 and DDI was independent of age, BMI, gender, and total cholesterol. Weaker correlations were found with FVIIc, FVIIIc, and PAI-1.
Conclusions:
- Free thyroxine (fT4) may play a physiological role in maintaining hemostatic balance in hyperlipidemic individuals.
- Lower fT4 levels are associated with a hypercoagulable state, indicating a potential link between thyroid function and thrombosis risk in this patient group.
Abstract:
High serum levels of cholesterol and triglycerides are risk factors for coronary heart disease and are strongly related to several haemostatic parameters. Thyroid disorders are a frequent feature in hyperlipidemic patients and are also associated with a variety of haemostatic abnormalities. Therefore, we analysed the relationships between free T4 (fT4) levels and Factor VII and VIII activities (FVIIc and FVIIc), D-Dimers (DDI) and Plasminogen Activator Inhibitor type 1 (PAI-1), in a group of 472 healthy patients referred for hyperlipidemia. Fourty patients were found to have primary hypothyroidism. A negative correlation was found in the whole study population between fT4 and DDI (p = 0.0001, r = -0.21) and the same results were found after exclusion of the patients with fT4 below the normal range (p = 0.0007, r = -0.17). In a multivariate regression analysis, the relationship between DDI and fT4 was independent of age, Body Mass Index (BMI), gender and total cholesterol. Less impressive correlation coefficients were found with FVIIc (r = -0.10), FVIIIc (r = -0.09) and PAI-1 (r = -0.09). These results suggest that fT4 may play a physiological role in the regulation of the haemostatic equilibrium in hyperlipidemic patients and that low levels of fT4 are associated with a hypercoagulable state.