Overview: Partial Thromboplastin Time TestIntroduction: The Partial Thromboplastin Time Test measures clotting time to diagnose bleeding disorders, causing excessive bleeding. Aligned with 2023 ISTH guidelines, it uses coagulation methods for high specificity, supporting coagulation screening. This test is critical for guiding diagnosis, treatment planning, and improving outcomes in coagulation for patients with suspected bleeding disorders, such as hemophilia or von Willebrand disease.
Other Names: APTT Assay, Activated Partial Thromboplastin Time Test.
FDA Status: Laboratory-developed test (LDT), meeting coagulation standards for diagnostic accuracy.
Historical Milestone: APTT testing began in the 1950s with coagulation factor research. Methods improved in the 2000s, enhancing diagnostic precision.
Purpose: Measures clotting time to diagnose bleeding disorders, guides treatment, and evaluates patients with excessive bleeding.
Test Parameters: 1. APTT Time
Pretest Condition: No fasting required. Collect citrated plasma. Report history of excessive bleeding or clotting disorder symptoms.
Specimen: Citrated Plasma (NaCit, 2-4 mL). Transport in a biohazard container.
Sample Stability at Room Temperature: 8 hours
Sample Stability at Refrigeration: 24 hours
Sample Stability at Frozen: Not frozen
Medical History: Document excessive bleeding, bruising, or history of bleeding disorders. Include current medications, especially anticoagulants.
Consent: Written consent required, detailing the tests purpose, bleeding disorder implications, and risks of sample collection.
Procedural Considerations: Uses coagulometry to measure activated partial thromboplastin time. Results are available in 1-2 days, supporting clinical decisions. Performed in laboratories, often for bleeding disorder diagnosis.
Factors Affecting Result Accuracy: Improper sample collection or anticoagulant contamination can affect results. Lupus anticoagulant may prolong APTT.
Clinical Significance: Prolonged APTT confirms bleeding disorders, guiding factor replacement or anticoagulant therapy. Normal results may require specific factor assays.
Specialist Consultation: Consult a hematologist for result interpretation and treatment planning.
Additional Supporting Tests: PT/INR, factor assays, or von Willebrand factor testing to confirm bleeding disorder diagnosis.
Test Limitations: Non-specific for certain bleeding disorders; clinical correlation is needed. Sample quality affects sensitivity.
References: ISTH Coagulation Guidelines, 2023; Journal of Thrombosis and Haemostasis, Connors JM, 2022.
