Summary
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 FVIIIc), 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.