What does the activated partial thromboplastin time (APTT) test measure factors including?

The activated partial thromboplastin time (APTT) test is a valuable laboratory test that primarily assesses the efficacy of the intrinsic and common coagulation pathways. The factors that are measured by this test include factors XII (Hageman factor), XI (plasma thromboplastin antecedent), IX (Christmas factor), II (prothrombin), V (proaccelerin), and X (Stuart-Prower factor).

By measuring the time it takes for blood to clot in response to specific reagents that activate the intrinsic pathway, APTT identifies deficiencies or abnormalities in these coagulation factors. This test is particularly important in evaluating conditions such as hemophilia A (associated with factor VIII deficiency) and hemophilia B (associated with factor IX deficiency), as well as in monitoring anticoagulant therapy like heparin.

Given this context, the factors listed in the correct answer directly relate to the components and functionality evaluated by the APTT test. Therefore, it accurately reflects the specific factors involved in the pathways assessed by this test.