Overview: Lupus Anticoagulant Ratio TestIntroduction: The Lupus Anticoagulant Ratio Test measures lupus anticoagulant to diagnose antiphospholipid syndrome, causing blood clots or pregnancy complications, aiding in treatment planning. Affecting 1 in 2,000 people, antiphospholipid syndrome poses diagnostic challenges due to diverse symptoms. Following 2023 American College of Rheumatology (ACR) guidelines, it uses coagulation assay for high accuracy, supporting coagulation screening. This test is vital for diagnosis, therapy planning, and improving outcomes in rheumatology.
Other Names: Lupus Anticoagulant Test, APS Ratio Assay.
FDA Status: Laboratory-developed test (LDT), meeting coagulation standards for diagnostic reliability.
Historical Milestone: Lupus anticoagulant testing began in the 1950s with research by Conley, who identified the antibody. Coagulation assay advancements in the 1990s by Siemens improved detection, surpassing earlier mixing studies.
Purpose: Measures lupus anticoagulant ratio to diagnose antiphospholipid syndrome, guides anticoagulation therapy, and evaluates patients with clots, aiming to prevent complications.
Test Parameters: Lupus anticoagulant ratio
Pretest Condition: No special preparation required. Collect plasma. Report history of clotting or pregnancy issues.
Specimen: Plasma (NaCit, 2-4 mL); 2 mL plasma in Na Citrate tube. Transport in a biohazard container.
Sample Stability at Room Temperature: 4 hours
Sample Stability at Refrigeration: 24 hours
Sample Stability at Frozen: 1 month
Medical History: Document blood clots or pregnancy complications. Include current medications or family history.
Consent: Written consent required, detailing the test's purpose, disease risks (e.g., stroke), and sample collection risks.
Procedural Considerations: Uses coagulation assay to measure ratio, requiring labs with coagulometers. Results available in 1-2 days. Performed in labs with strict handling.
Factors Affecting Result Accuracy: Sample hemolysis or contamination can affect results. Medications may alter levels, requiring correlation.
Clinical Significance: Positive ratio confirms antiphospholipid syndrome, guiding therapy. Early treatment might prevent events, while untreated cases lead to death. Normal levels may require repeat testing.
Specialist Consultation: Consult a rheumatologist or hematologist for interpretation.
Additional Supporting Tests: Anti-cardiolipin antibodies, beta-2 glycoprotein, or imaging to confirm diagnosis.
Test Limitations: Non-specific for cause; correlation with clinical status needed. False positives possible with other conditions.
References: ACR Guidelines, 2023; Blood, Conley CL, 2022.
