From the Guidelines
To diagnose coagulation disorders, order the following labs: Prothrombin Time (PT), Activated Partial Thromboplastin Time (aPTT), and Fibrinogen levels, as these standard coagulation tests are widely accepted and utilized in clinical practice, as supported by the most recent evidence 1. When evaluating coagulation disorders, it is essential to consider the patient's overall clinical presentation and medical history. The following tests provide a comprehensive evaluation of the clotting cascade:
- Prothrombin Time (PT) and International Normalized Ratio (INR) to evaluate the extrinsic clotting pathway
- Activated Partial Thromboplastin Time (aPTT) to evaluate the intrinsic clotting pathway
- Fibrinogen level to assess clot formation and breakdown Additional tests, such as D-dimer, Factor V Leiden mutation, Prothrombin G20210A mutation, Antiphospholipid antibodies panel, Protein C, Protein S, and Antithrombin III activity, may be considered based on the patient's specific clinical presentation and risk factors, as suggested by recent studies 1. It is crucial to note that anticoagulant therapy can affect the results of these tests, and caution should be exercised when interpreting results in patients on anticoagulation therapy, as highlighted in recent research 1. If anticoagulation cannot be stopped, consider repeating abnormal results to confirm findings, as some factors can be temporarily altered by acute illness or inflammation. Viscoelastic coagulation tests, such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM), may also be useful in detecting coagulopathy associated with direct oral anticoagulants (DOACs) and guiding reversal therapy, as demonstrated in recent studies 1.
From the Research
Coagulation Disorder Diagnosis
The diagnosis of coagulation disorders involves various laboratory tests to assess the patient's blood clotting ability. The following tests are commonly used:
- Complete blood cell count
- Platelet count
- Prothrombin time (PT) 2, 3, 4, 5, 6
- Activated partial thromboplastin time (APTT) 2, 3, 4, 5, 6
- Evaluation of a peripheral blood sample
- Fibrinogen level 3, 6
- Thrombin time (TT) 6
- Von Willebrand factor antigen and activity assays 2, 3
- Template bleeding time 2
- Multimeric analysis of von Willebrand factor 2, 3
Specific Tests for Coagulation Disorders
Certain tests are used to diagnose specific coagulation disorders, such as:
- Factor VIII and factor IX assays to diagnose hemophilia A and B 3
- Von Willebrand factor antigen and activity assays to diagnose von Willebrand disease 2, 3
- Ristocetin cofactor assay to measure von Willebrand factor activity 2, 3
- Mixing study to assess factor deficiencies or inhibitors 3, 5
- Factor inhibitor assays to diagnose acquired hemophilia or other factor inhibitors 3
Interpretation of Test Results
The interpretation of coagulation test results requires careful consideration of the patient's clinical presentation, medical history, and laboratory results. Abnormal test results may indicate a coagulation disorder, and further testing may be necessary to confirm the diagnosis 4, 5, 6.