Serum Levels of Vitamin D and Haemostatic Factors in Healthy Subjects: The Tromsø Study

Abstract

Background: Receptors for vitamin D have been found in various tissues, including the vascular endothelium. The role of vitamin D in the haemostatic process is uncertain, but in vitro studies may indicate a pro-fibrinolytic effect. Methods: Two hundred and six subjects (105 males) were included in the study. The relations between indices of calcium metabolism and haemostatic factors [tissue plasminogen activator antigen (tPA Ag), plasminogen activator inhibitor 1 (PAI-1), prothrombin fragment 1+2, activated factor VII and total factor VII coagulant activity] and high-sensitivity C-reactive protein (HS-CRP) were examined. Results: There were significant and negative correlations between serum 25(OH) vitamin D and PAI-1 and tPA Ag, and between serum 1,25(OH)₂ vitamin D and tPA Ag and HS-CRP. In a multiple linear regression model with age, gender, body mass index and smoking status as covariables, only the relation between 25(OH) vitamin D and tPA Ag was significant. There were no significant relations between any of the haemostatic factors tested and serum parathyroid hormone. Conclusion: It appears that the serum level of vitamin D is related to fibrinolytic activity and to the integrity of the vascular endothelium, but the clinical importance of this observation remains to be determined.