Geisinger Medical Laboratories/Geisinger Proven Diagnostics Test Catalog

Order Display Name: Geisinger Epic Procedure Code Or ID CPT Code:  

PT/APTT MIXING STUDIES

ORDERING INFORMATION:
Geisinger Epic Procedure Code: LAB2948         Geisinger Epic ID: 14541

SPECIMEN COLLECTION
Specimen type:
Platelet-free plasma
Preferred collection container:
Alternate Collection Container:
Other size blue-top (3.2% sodium citrate) tubes (e.g., 1.8 mL, 4.5 mL)
Specimen required:
Two (2) 1 mL aliquot of plasma.
Special notes:
Collect two (2) citrated blue-top tubes. Avoid contaminating the sample with tissue thromboplastin or heparin. Venipuncture must be performed with no trauma. If blood is drawn from an indwelling catheter, flush with 5 mL of saline and discard the first 5 mL of blood collected. If blood is drawn with a butterfly device, draw a discard tube first to remove air from tubing.

SPECIMEN PROCESSING
Specimen processing instructions:
Centrifuge the citrated blue-top tubes as soon as possible (within 60 minutes) at designated time and speed to obtain platelet-poor plasma (<10,000/µL). Using a plastic pipette, remove 1 mL of plasma and transfer to a plastic polypropylene aliquot tube and label with patient's name and a second patient identifier (e.g., date of birth, medical record number). Freeze upright and transport on dry ice. 
Transport temperature:
Frozen.
Specimen stability:
Frozen: -20°C for 30 days, -70°C for 6 months. Room temperature: 4 hours.
Rejection criteria:
Clotted specimen. Stability limits exceeded. Overfilled or underfilled tubes. HCT > 55 requires rejection, reorder, and recollection with proper adjustment of anticoagulant. Indications of thaw in transit are sample on slant in aliquot tube or in lid of tube. These samples will be run but will receive a comment of interpret results with caution as thawing suspected.

TEST DETAILS
Reference interval:
PT or PT heparin neutralized: 11.5 - 14.6 sec. aPTT or aPTT heparin neutralized: 21-38 sec.
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 indicates factor deficiency(ies) state. Partial or No Correction as seen with a Rosner index >15 suggests an inhibitor. Further testing to quantitate the inhibitor is available.
Additional information:
Mixing study only performed if elevated PT and/or aPTT.
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); PT (Baseline); PT Heparin neutralized, aPTT Heparin neutralized, aPTT Mix, PT Mix (Please place on new line)Baseline = patient plasma only, Mix = patient plasma + normal control plasma tested immediate after mixing and again after a 60 minute incubation.
Methodology:
Mechanical Clot-Based
Synonyms:
PT/PTT Mixing Study
50/50 Mixing Study, A5050
Mixing Study
Clinical significance:
This test is used to determine the cause of a prolonged aPTT and/or PT.
Doctoral Director(s:)
Michelle Grant DO    
Review Date: 01/11/2020

Performing Locations

Geisinger Medical Center

Performing laboratory: Coagulation
Technical Lead: Margaret Knowles-Tuchman
Frequency: Daily, 1st shift
Performed stat? No

Geisinger Wyoming Valley Medical Center

Performing laboratory: ATL+
Technical Lead: Julia Bell    
Frequency: Monday-Friday 0600-1330, Saturday, Sunday 0600-1300    
Performed stat? No
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