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Epic Code LAB326 Mixing Studies, APTT

Important Note

There is currently a nationwide shortage of this tube. Please take steps to ensure specimen integrity to reduce recollection. Specimen Tube Shortage (link)

Test Name Alias

Mixing Studies APTT | 4120


Interface Order Alias




Quick Collect


Clinical Information

The mixing study is used to evaluate a prolonged activated partial thromboplastin time.   It is an effective screening tool for coagulation factor deficiencies or abnormalities in the intrinsic and common pathway.  Additionally, it is utilized to detect coagulation inhibitors. 


Collection Instructions

Specimen Collection: Blood


Container(s): (3) 3.2% Na Citrate Tube (blue top)

Preferred Volume to Collect: 8.1 mL (3 full 2.7 mL tubes)

Minimum Volume to Collect: 5.4 mL (3 full 1.8 ml tubes)

Capillary collect ok: No

Microtainer acceptable: No


Collection Instructions:

  • Detailed instructions (link): Blue Citrate Tube

  • Specimen should be processed within 1 hour – See Processing Instructions below.


Processing Instructions (Laboratory, Outpatient or Off-site collection)

  • Processed Specimen: Platelet Poor Plasma
  • Centrifuge/Spin: Yes
  • Aliquot: Yes
  • Processing Instructions:
  • Transport Temperature:
    • Ambient (up to 1 hour in whole blood state)
    • Frozen (plasma only >1 hour)


Rejection Criteria

  • Hemolysis
  • Specimen has been thawed


Specimen Stability

  • Ambient: 1 Hour Whole Blood
  • Frozen: 2 months – Platelet poor plasma; aliquoted and frozen within 1 hour of collection
  • Laboratory Retention: 2 months


Reflex Information

Link: Mandatory Reflex Testing approved by MEC


Reflex testing may include the following: lupus screen and associated tests.


Test Frequency

Available Monday-Friday, usual TAT 1-4 days.


Reference Range

Effective 9/26/2023 at 9 am

  • 24-34 seconds (Corewell Health Reference Lab, Grand Rapids, CS 5100 Analyzer)

  • 23-28 seconds (Corewell Health Reference Lab, Grand Rapids, BCS XP analyzer)

Performing Department


Performing Department Laboratory Location

Corewell Health Reference Laboratory, Grand Rapids, MI



Activated partial thromboplastin clot based assay.




CDM Code


Epic Test ID


Mayo Access Code



Reviewed Date


Last Update

09/26/2023, 09:08: Reference Range