Prothrombin concentrations in middle-aged men and women – stability over time and correlations with cardiovascular risk factors

Prothrombin is a vitamin K-dependent glycoprotein synthesized in the liver and circulating in blood as an inactive zymogen. The corresponding activated thrombin enzyme is a central player in hemostasis and thrombosis. Still, little is known about the individual variation over time of the prothrombin concentration in plasma in the general population. This study aimed to establish the prothrombin plasma level and its correlation with cardiovascular risk factors in the general population. A novel aptamer-based electrochemical biosensor, which in a single, direct incubation step and within five minutes quantifies the prothrombin concentration in molar amounts, was used for analysis of plasma samples from 141 non-anticoagulated individuals in the Swedish cardiopulmonary bioimage study (SCAPIS). Plasma samples from baseline and from re-examination after one year of follow-up were tested. The study population consisted of 141 individuals with a mean age of 57.3 (standard deviation 3.79) years, and 66 (47%) were females. The mean (±standard deviation) prothrombin concentrations in plasma were 1565 nM (±249) and 1526 nM (±319) at baseline and one-year follow-up, respectively. There was a strong correlation between the individual prothrombin concentration at baseline and one year later, r=0.658, p<0.001. Baseline prothrombin plasma levels correlated positively and weakly with weight (r=0.183, p=0.030), waist (r=0.213, p=0.011), waist-hip-ratio (r=0.191, p=0.023), body mass index (r=0.244, p=0.004), cholesterol (r=0.281, p<0.001), LDL-cholesterol (r=0.220, p=0.009), triglycerides (r=0.257, p=0.002), and thrombocytes (r=0.170, p=0,046). Plasma levels of prothrombin are stable over time in most individuals and are positively and weakly correlated with cardiovascular risk factors. • Prothrombin is a zymogen that is activated to thrombin and a key player in hemostasis and thrombosis. • Little is known about the prothrombin levels in plasma in the general population. • We show that the prothrombin level in individuals is stable after 1 year follow up. • Prothrombin is correlated to obesity measures and lipids • Prothrombin levels in plasma indicate a link to cardiovascular risk factors.