Factor VIII Activity:
Why Factor - VIII Activity Test?
CLINICAL INFORMATION
Haemophilia is a disease where blood does not clot properly. Each time a person bleeds, it triggers a series of reactions known as the coagulation cascade to form clots to stop bleeding. Clotting factor tests are also called ‘factor assays tests’ or “screening for factor assays” are required to diagnose bleeding disorders. Other screening tests for detecting clotting disorders include CBC (looks for any abnormalities in RBCs, WBCs and mainly the abnormalities seen platelets and in the platelet count), activated partial thromboplastin time (APTT): This test looks for how long it takes for blood to clot and hence if any of these clotting factors are too low then clotting will take longer time, Prothrombin time (PT): It measures the time taken to form a clot as it measures the clotting ability of factors I, II, V, VII and X and thus if any of these clotting factors are too low then clotting will take longer time, Fibrinogen test is also known as Factor 1 Test: This test is performed when the patient has abnormal PT or APTT test results, clotting factor tests also known as Factor Assays: This test assay helps to screen for diagnosis of bleeding disorder as in case of haemophilia and also to assess its severity (i.e this test helps inaccurate classification of haemophilia) etc. Patients before this test must not have received medications such as Coumadin, warfarin, blood thinners, heparin therapy like LMWH etc, since it will interfere with the true test results. Other factors which may influence the test results are vitamin K deficiency and conditions like liver diseases, lupus anticoagulants etc. Factor VIII is a protein synthesized by the liver and is also called an anti-hemophilic factor, which plays a key role in the intrinsic clotting cascade. Factor VIII activity test helps to diagnose or monitor the treatment for haemophilia A (inherited deficiency of factor VIII). The F8 gene encodes for clotting factor protein VIII synthesis. High levels of Factor VIII is an indication for thrombosis (such as blood clot formation in the blood vessels). High levels of factor VIII may be due to older age, diabetes, obesity, pregnancy, surgery, chronic inflammation, malignancy, liver diseases, hyperthyroidism, intravascular hemolysis, renal diseases etc. Decrease in factor VIII may be due to haemophilia A (inherited deficiency of factor VIII), Von Willebrand disease, DIC, presence of autoantibodies against factor VIII (i.e presence of factor VIII inhibitor) etc. In most cases, it is seen that the levels of factor VIII are always proportionally elevated with a concordant increase in vWF (Von Willebrand’s factor). Factor VIII activity test: This test is useful for diagnosing haemophilia A (inherited deficiency of factor VIII), assessing the impact of liver diseases on hemostasis, investigating a prolonged partial thromboplastin time etc. Hemophilia A may require both - one-stage clot-based factor VIII activity test and also chromogenic factor VIII test, Bethesda assay test activities for the diagnosis and to monitor the activity of factor VIII activity. Moreover, the activity of factor VIII can be studied by a monoclonal antibody study termed – “Emicizumab” which is a bi-specific antibody that helps in the study. This test is also useful for diagnosing for assessing the impact of liver diseases on hemostasis, investigation of a prolonged partial thromboplastin time etc. This test also helps to study the diagnostic cause for muscle haemorrhage, hematomas, menorrhagia, epistaxis, monitoring coagulation factor replacement therapy etc. Hence positive test results for Factor VIII deficiency may be predisposed due to either congenital causes like haemophilia A/ factor VIII - Hemophilia or due to acquired causes such as vitamin K deficiency, warfarin overdose, liver diseases, consumptive coagulopathy, DIC etc. Other additional tests include stool test and urinalysis, genetic testing etc.
General Instructions:
Sample Requirement: Specimen - Blood sample collected from the vein. Test Preparation: None.
NOTE - Sample for specimen collections may vary based on the patient’s condition/cases according to the patient’s presenting complaints/signs or symptoms:
SPECIMEN REQUIREMENT (Special or Rare Cases) - As instructed and guided by Physician / Clinician / Pathologist / as per Laboratory’s requirements, according to procedures and protocols.
This Multi-Specialty Clinical Referral Laboratory RT DIAGNOSTICS provides precise and accurate tests with an extensive range of testing services to the medical centres to help in the diagnosis and identification of pathology in the test specimens for infectious diseases and also to evaluate the function of organ systems of the patient. It prevents further complications and helps to stabilize and restore health to near normalcy at the earliest without delay.
