Thrombin Generation Increasing with Age and Decreasing with Use of Heparin Indicated by Calibrated Automated Thrombogram Conducted in Chinese

Objective Calibrated Automated Thrombogram（CAT） is a test to monitor the generation of thrombin. It can be described by four parameters： lag time, peak thrombin, endogenous thrombin potential （ETP） and time to peak （ttPeak）. This study aims to determine the normal ranges of CAT parameters in Chinese, and evaluate whether thrombin generation is correlated with the concentration of heparin/Iow molecular weight heparin. Methods Plasma from 120 healthy subjects were collected to determine the normal rangea of CAT parameters in Chinese. Normal plasma pool （NPP, n=25） spiked with different concentrations of heparin or enoxaparin were used to detecte CAT parameters. The overall and age specific normal ranges of CAT parameters were calculated using descriptive statistics method with mean＋-2SD. The correlation between CAT parameters and age or concentrations of heparin, enoxaparin were analyzed with linear regression model. Results The normal ranges for lag time, peak thrombin, ETP, ttPeak in the subjects were 3.648＋2.465 min, 367.39＋151.93 nmol/L, 2277＋_1030 nmol/L.min and 6.372＋_4.280 min respectively. Age was linearly correlated with lag time （r=-0.6583, P〈0.0002）, peak thrombin （r=0.4863, P〈0.0002）, ETP （r=0.3608, P〈0.0014） and ttPeak （r=-0.6323, P〈0.0002）. The values of ETP/peak ratio were linearly correlated with concentrations of heparin. Conclusion The normal ranges of four CAT parameters for Chinese were determined. CAT parameters are associated with age. ETP/peak ratio could be used to monitor the process of anticoagulation therapy.