ABSTRACT
<p><b>OBJECTIVE</b>To explore the distribution and influence factors of protein C (PC), protein S (PS) and antithrombin (AT) activities and to determine the prevalence of their deficiencies in the Chinese Han healthy population.</p><p><b>METHODS</b>Healthy volunteers including blood donors and individuals for routine check-up were recruited from 4 Chinese medical centers. The plasma levels of PC, PS and AT activities were measured. The plasma levels of activities were measured by chromogenic substrate assay (AT and PC) and clotting assay (PS).</p><p><b>RESULTS</b>A total of 3493 healthy Chinese adults had been recruited in this study. Males had higher PS and PC activities than females, especially for PS (P < 0.01). PC activities increased with age in both sexes but decreased in men after 50 years old. There was no significant change with age were of PS in 50 years old, while there was a decline in males and a rise in females above 50 years old. AT tended to increase with age in women but decreased with age in men after 50 years old. Based on the age and gender, the general prevalence of PC, PS and AT deficiencies in the general Chinese Han population were 1.15%, 1.49% and 2.29%, respectively.</p><p><b>CONCLUSION</b>PC, PS and AT activities have correlation with age and gender in Chinese Han population. Reference range should be laid down and deficiencies should be identified</p>