Elevated factor VIII activity and venous thromboembolism in patients referred to the Iranian Blood Transfusion Organization: A case control study

Abstract Objective A high plasma level of factor eight (FVIII) is a risk factor for venous thromboembolism (VTE). Since, there was no report about the association of elevated FVIII and VTE in Iranian population, the incidence of elevated FVIII and its association to VTE was evaluated. Materials and methods 152 consecutive idiopathic VTE patients referred to the Iranian Blood Transfusion Organization (IBTO) and 130 healthy matched blood donors were studied. At least one confirmed idiopathic deep vein thrombosis (DVT) or pulmonary embolism (PE) was found among all cases. The blood samples were collected at least 3 months after DVT/PE diagnosis. The normal reference range was determined by using the Control samples of the donors. FVIII levels were measured using PTT based one-staged assay. Results The FVIII levels in the cases and controls were 157.3 ± 53.4 and 111.8 ± 29.7, respectively. In cases, the lowest and the highest levels of FVIII were 66 IU/dl and 364 IU/dl, while they were 42 IU/dl and 195 IU/dl for the controls. There was no relation between gender, age and FVIII level in either group. The normal reference range for the controls was 52–171 IU/dl. Considering the cut-off point as 180 IU/dl, the elevated values were seen in 28.9% of the case group vs. 3.1% of the control group. Conclusion Elevated factor VIII is likely to be a risk factor for VTE. Moreover, a new normal reference range for the Iranian population was defined.