Subunit antigen and activity levels of blood coagulation factor XIII in healthy individuals - Relation to sex, age, smoking, and hypertension

Factor (F) XIII covalently cross-links and stabilizes the fibrin-clot. Rece nt evidence suggests a role for FXIII in atherothrombotic diseases, bur no information is available regarding the association of FXIII with common ris k factors. The aim of this study was to investigate the relationship of FXI II with age, sex, smoking, and hypertension. Plasma levels of FXIII A-subun it antigen, FXIII B-subunit antigen, and FXIII cross-linking activity were measured in 612 healthy individuals (250 men and 362 women). FXIII A- and B -subunit levels were correlated significantly with age in both men (r=0.21, P=0.001, and r=0.17, P=0.008, respectively) and women (r=0.20, P<0.0005, a nd r=0.13, P=0.011, respectively). FXIII B-subunit levels and activity were correlated significantly with FXIII A-subunit levels (r=0.60, P<0.0005, an d r=0.14, P<0.0005, respectively) and fibrinogen (r=0.26, P<0.0005, and r=0 .14, P=0.001, respectively). Women had higher levels of FXIII A-subunit (11 1.8% versus 105.2%, P<0.01) and B-subunit (109.5% versus 103.8%, P<0.01) th an did men, FXIII A-subunit was significantly increased in smokers (117.0% versus 104.6%, P<0.0005) and in subjects with hypertension (114.9% versus 1 07.8%, P<0.05). In a multiple regression model, FXIII A-subunit was signifi cantly increased by female sex (+6.4%, P<0.007), smoking (+12.3%, P<0.0005) , and increasing age (+3.7% per 10 years, P<0.0005). FXIII B-subunit was si gnificantly related to female sex and fibrinogen, and FXIII activity was si gnificantly related to fibrinogen levels. In conclusion, the FXIII A-subuni t level increases significantly with female sex, age, and smoking, whereas FXIII B-subunit and FXIII activity are associated with FXIII A-subunit leve l and fibrinogen. Although evidence for a causal relationship between FXIII A-subunit and vascular disease is not available, these results might sugge st a role for elevated FXIII A-subunit levels in the pathogenesis of vascul ar disease.