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Geisinger Medical Laboratories/Geisinger Proven Diagnostics Test Catalog
PT/APTT MIXING STUDIES |
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ORDERING INFORMATION: |
Geisinger Epic Procedure Code: LAB2948 Geisinger Epic ID: 14541 | |
SPECIMEN COLLECTION |
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Specimen type: |
Platelet-poor plasma | |
Preferred collection container: |
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Alternate Collection Container: |
Other size blue-top (3.2% sodium citrate) tubes (e.g., 1.8 mL, 4.5 mL)
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Specimen required: |
Two (2) 1 mL aliquots | |
Special notes: |
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| SPECIMEN PROCESSING |
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Specimen processing instructions: |
Centrifuge specimen immediately at designated time and speed to obtain platelet-poor plasma (<10,000/µL). Using a plastic pipette, carefully remove plasma from cells, avoiding platelet/buffy layer by leaving a thin layer of plasma on top the cells. The centrifuged plasma should be aliquoted (1 mL per aliquot) into clearly labeled polypropylene tubes. The number of tests ordered will determine the aliquots needed. Check the residual specimen for clot and if present discard sample and redraw specimen. If plasma is icteric, lipemic or hemolyzed a lab comment should be generated to notify staff. Freeze upright in non-thaw freezer. | |
Transport temperature: |
Frozen | |
Specimen stability: |
Room temperature: 4 hours Frozen (plasma) -20°C: 2 weeks Frozen (plasma) -70°C: 6 months |
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Rejection criteria: |
Clotted, hemolyzed, improperly filled tubes, improper anticoagulant ratio (HCT >55% and citrate not adjusted), refrigerated specimens, or stability exceeded.
Note: Specimens suspected of thawing in transport, indicated by slant in aliquot or specimen in lid of tube, will have testing performed, and the comment “interpret results with caution as thawing suspected” added to results. |
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TEST DETAILS |
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Reference interval: |
PT or PT heparin neutralized: PT 11.6-15.2 seconds aPTT or aPTT heparin neutralized: 21-38 seconds |
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Interpretation guide: |
Correction of PT or aPTT is defined as test returning to reference range after mixture with normal pooled plasma or Rosner Index <15. Correction indicates a factor deficiency(s) state. Partial or No Correction as seen with a Rosner index >15 suggests an inhibitor. Interpretation guidelines are built into the testing algorithm. |
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Additional information: |
Mixing study only performed if elevated PT and/or aPTT. If PT and/or aPTT normal only original value will be reported. | |
CPT code(s): |
85611 | |
| Note: The billing party has sole responsibility for CPT coding. Any questions regarding coding should be directed to the payer being billed. The CPT codes provided by GML are based on AMA guidelines and are for informational purposes only. | ||
Test includes: |
aPTT(Baseline/Mix); PT (Baseline/Mix), heparin level, heparin neutralization, thrombin time, and fibrinogen. Baseline = patient plasma only. Mix = patient plasma + normal control plasma tested immediately after mixing and again after a 60-minute incubation. |
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Methodology: |
Mechanical clot-based |
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Synonyms: |
PT/PTT Mixing Study 50/50 Mixing Study, A5050 Mixing Study
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Clinical significance: |
This test is used to investigate the cause of a prolonged aPTT and/or PT. | |
Doctoral Director(s:) |
Michelle Grant DO | |
| Review Date: | 03/31/2023 | |