Geisinger Medical Laboratories/Geisinger Proven Diagnostics Test Catalog

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

ANTITHROMBIN III ACTIVITY

ORDERING INFORMATION:
Geisinger Epic Procedure Code: LAB1770         Geisinger Epic ID: 17587

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:
1 mL aliquot plasma.
Special notes:
  • Ideally the patient should not be receiving anticoagulant medication as it may interfere with testing and cause erroneous results. See Anticoagulation Impact on Coagulation Tests.
  • If the patient’s hematocrit (HCT) is >55%, the volume of anticoagulant in the tube should be adjusted. Contact a performing location for special tube preparation to reduce the citrate in the collection tube. For those patients with HCT >65.4% see LAB3632 Stago Sodium Citrate Adjustment Chart for formula to determine amount of citrate removal required.
  • When possible, use fresh venipuncture to collect blood to avoid activation of coagulation by tissue thromboplastin. Blood may be drawn from an indwelling catheter or vascular access device. Draw sample from a lumen that has not been heparinized or flush the line with 5 mL of saline, and discard or use for other purposes the first 5-10 mL of blood.
  • Butterfly device collections, draw a discard tube first to remove air from collection tubing.
  • Tubes should be >90% filled.
  • Immediately mix gently after collection by inverting the tube end over end 5 to 6 times. Avoid vigorous mixing or additional inversion. Observe for the presence of clots. Recollect if fibrin clots observed.
  • Transport at ambient temperature to processing location and processing should be completed within 8 hours.
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: 8 hours.
Rejection criteria:
 Clotted specimen. Underfilled or overfilled tube. Stability limits exceeded. If HCT > 55%, cancel test and reorder/recollect 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:
 80-120%.
Additional information:
 Anticoagulation Impact on Coagulation Tests
CPT code(s):
 85300
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:
 Antithrombin level.
Methodology:
Chromogenic
Synonyms:
AT3
Antithrombin 3
Antithrombin
Clinical significance:
Antithrombin 3 (AT3) is a blood protein produced in the liver that naturally prevents clot formation. AT3 works with heparin to stop clot production mainly by inhibiting thrombin (factor IIa) and factor Xa. Low AT3 levels increase risk of blood clots in patients and decrease response to heparin therapy. AT3 levels are low during or immediately after a blood clot, in patients with kidney or liver disease, and during heparin therapy.
Doctoral Director(s:)
Michelle Grant DO    
Review Date: 02/09/2023

Performing Locations

Geisinger Medical Center

Performing laboratory: Coagulation
Technical Lead: Margaret Knowles-Tuchman
Frequency: Daily, all shifts
Performed STAT? Yes

Geisinger Wyoming Valley Medical Center

Performing laboratory: ATL+
Technical Lead: Mary Glazenski    
Frequency: Daily, all shifts    
Performed STAT? Yes

Geisinger Community Medical Center

Performing laboratory: Hematology
Technical Lead: Robert Furcon  
Frequency: Daily    
Performed STAT? Yes
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