Is it the factor V activity assay or the factor V Leiden test?
Physicians occasionally order a factor V activity assay to help diagnose liver disease or to establish the presence of a rare inherited factor V deficiency in infant bleeding. Because the factor V Leiden mutation is present in 3-8 percent of Europeans, Arabs and Hispanics and confers a two to eight-fold risk of thrombosis (80-fold when homozygous), the factor V Leiden test is an important part of a thrombophilia test profile (see Problem 1). Laboratories should screen using the phenotypic activated protein C resistance (APCR) assay and confirm with the molecular test. 2. Is it the factor II (prothrombin) activity assay or the factor II (prothrombin) 20210 mutation test? Physicians rarely order the factor II activity assay to establish the possibility of an inherited deficiency. The factor II (prothrombin) 20210 mutation is present in 2-3 percent of Europeans and confers a two to six-fold risk of thrombosis, making it an important part of the thrombophilia risk testing. 3. Is it the fac
