Values of Blood Coagulating Factors Vary with Ambient Temperature

Seasonal influence on mortality from cardiovascular and cerebrovascular diseases is well documented. Understanding the seasonal variations in cardiovascular risk factors can shed light on this phenomenon. Elevation of coagulation factors during cold weather may in part explain the higher mortality from myocardial infarction and stroke in winter. The Cardiovascular Disease Risk Factors Community Study (CVDFACTS) included subjects belonging to 2 cohorts located in northern and southern Taiwan. This study included 2877 subjects aged 18 and above whose blood levels were examined for various coagulating factors. Besides measuring conventional cardiovascular risk factors including: blood pressure, body mass index and total cholesterol, values for blood fibrinogen, factor VII activity, factor VIII activity, plasminogen, antithrombin III, prothrombin time and activated partial thromboplastin time were determined for all subjects. Of these hemostatic parameters, levels of all, except prothrombin time, were statistically different between days with mean temperature >20 °C and days with temperature <20 °C (P>0.01). In cold weather, a greater tendency to clot in circulatory system was demonstrated in this study, indicating seasonal variations may be demonstrated in this subtropical region.