Background and Objective: Deep vein thrombosis (DVT) is one of the most common forms of venous thromboembolism (VTE). Deficiency in natural anticoagulant proteins is considered to be the major cause of thrombosis. In the present study, we investigated the incidence of defects in protein S, protein C, antithrombin and resistance to activated protein C (APC-R) in patients with DVT referred to the Iranian Blood Transfusion Organization (IBTO). Results were compared with findings from other studies performed in the other nations.

Materials and Methods: In this descriptive study, a total of 656 patients with DVT were evaluated for the deficiency of natural anticoagulant proteins, including protein S, C, antithrombin and APC-R. After eliminating patients with acquired risk factors for thrombosis, defects in the aforementioned proteins were examined in 141 cases. The results were compared with the results of other studies using the Z score calculation.

Results: Protein S deficiency with 12.7% of cases was the most prevalent defect in our study. A defect in APC-R, which was found in 4.9 percent of cases, was the second prevalent deficiency. Moreover, AT and PC deficiencies with a prevalence rate of 2.8 and 2.1%, had the lowest rate in patients with DVT, respectively.

Conclusion: Protein S deficiency was the most common anticoagulant protein deficiency in patients with DVT referred to IBTO. The results obtained in this study are in concordance with the studies conducted in Middle East and other Asian countries. However, significant differences between our results and findings from studies performed in western nations exist.