From the Guidelines
To investigate underlying causes of thrombocytopenia and impaired coagulation profile, I recommend a comprehensive panel including complete blood count with peripheral smear, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen level, D-dimer, liver function tests, renal function tests, vitamin K levels, and specific tests for suspected conditions such as disseminated intravascular coagulation (DIC) panel, ADAMTS13 activity for TTP, heparin-induced thrombocytopenia antibodies, bone marrow aspiration/biopsy, and autoimmune markers like antiphospholipid antibodies. These tests are essential for determining the underlying cause of thrombocytopenia and coagulation abnormalities, which can be due to various conditions such as liver disease, DIC, vitamin K deficiency, certain medications, autoimmune disorders, or bone marrow problems 1. The combination of quantitative measurements (platelet counts, coagulation times) with qualitative assessments (peripheral smear morphology) provides crucial information about both the severity and potential causes of the bleeding disorder. Key tests to include are:
- Complete blood count with peripheral smear to assess platelet count and morphology
- Prothrombin time (PT) and activated partial thromboplastin time (aPTT) to evaluate coagulation pathways
- Fibrinogen level and D-dimer to assess fibrinolysis and thrombosis
- Liver function tests and renal function tests to evaluate organ function
- Vitamin K levels to assess for deficiency
- Specific tests for suspected conditions such as DIC panel, ADAMTS13 activity for TTP, heparin-induced thrombocytopenia antibodies, bone marrow aspiration/biopsy, and autoimmune markers like antiphospholipid antibodies. It is also important to consider the patient's medical history, medications, and lifestyle factors that may contribute to thrombocytopenia and coagulation abnormalities, as recommended by the American Heart Association/American Stroke Association 1. Blood samples should be collected before initiating any treatment that might affect coagulation, and results are typically available within 24-72 hours depending on test complexity. This comprehensive approach is necessary to guide appropriate management and improve patient outcomes, particularly in terms of morbidity, mortality, and quality of life.
From the Research
Blood Tests for Thrombocytopenia and Impaired Coagulation Profile
To investigate the underlying causes of thrombocytopenia and impaired coagulation profile, the following blood tests are recommended:
- Complete blood count (CBC) to confirm thrombocytopenia and evaluate other blood cell lines 2, 3, 4, 5
- Peripheral blood smear review to examine platelet morphology and detect any abnormalities 2, 3, 4, 5
- Prothrombin time (PT) and activated partial thromboplastin time (aPTT) to evaluate coagulation profile 2
- Platelet count in a tube containing heparin or sodium citrate to exclude pseudothrombocytopenia 3
- Tests for von Willebrand disease, such as von Willebrand factor antigen, von Willebrand factor activity, and factor VIII assays, if suspected 2
- Bone marrow examination to evaluate bone marrow platelet production, if necessary 4
Specific Tests for Underlying Causes
Depending on the clinical presentation and suspected underlying cause, additional tests may be ordered, such as:
- Tests for immune thrombocytopenic purpura (ITP), such as platelet antibody tests 6, 3, 5
- Tests for drug-induced thrombocytopenia, such as drug-dependent antibody tests 3, 5
- Tests for hepatic disease, such as liver function tests and hepatitis serologies 3, 5
- Tests for thrombotic microangiopathies, such as ADAMTS13 activity and schistocyte count 3
Interpretation of Test Results
Interpretation of test results should be done in conjunction with clinical presentation and medical history. Abnormal results may indicate an underlying condition that requires further evaluation and treatment. For example: