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Epic Code LAB1230880 APTT Direct Thrombin Inhibitor (APTT DTI) Inpatient Only

Important Note

Specimen tube must be full.

Test Name Alias

Activated Partial Thromboplastin Time | APTT DTI | APTT

Interface Order Alias


Clinical Information

The direct thrombin inhibitors which include argatroban, bivalirudin, and dabigatran, reversibly bind and inhibit thrombin, thereby suppressing the coagulation at the last stage of the cascade. When heparin induced thrombocytopenia is suspected or confirmed argatroban or bivalirudin may be used as an alternate anticoagulant for unfractionated heparin and low molecular weight heparin.

Ordering Instructions

Test orderable specific for patients on Direct Thrombin Inhibitors: Argatroban, Dabigatran, and bivalirudin

Collection Instructions

Specimen Collection: Blood


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

Preferred Volume to Collect: 2.7 mL (full tube)

Minimum Volume to Collect: 1.8 mL (full tube)

Capillary collect ok: No

Microtainer acceptable: No


Collection Instructions:

  • Detailed instructions (link): Anticoagulant Correction for High Hematocrit

  • Detailed instructions (link): Blue Citrate Tube

  • Specimen should be processed within 4 hours – See Processing Instructions below.
    • Specimens collected from patients receiving heparin therapy must 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
  • Instructions:
    • Detailed instructions (link): Preparing Platelet Poor Plasma
    • Separate plasma into 1 – 2 aliquots, minimum of 0.5 mL each.
    • Freeze aliquots in plastic transport tubes immediately.

Transport Temperature:

  • Ambient (up to 4 hours in whole blood state, 1 hour for patients on heparin therapy)
  • Frozen (plasma only >4 hours)

Rejection Criteria

  • Hemolysis
  • Specimen has been thawed

Specimen Stability

Ambient: up to 4 hours in whole blood state if the patient is not on heparin

Refrigerate: Not Acceptable

Frozen: Aliquot and freeze platelet poor plasma within 1 hour of collection if the patient is on heparin. Also freeze if >4 hours post collection plasma.

Laboratory Retention: 24 hours

Test Frequency

Available 24 hours, usual TAT 1 day.

Reference Range

  • 21-27 seconds See individual direct thrombin inhibitor (argatroban, bivalirudin) nomograms for therapeutic range

Laboratory Critical Values Table

Performing Department


Performing Department Laboratory Location

Spectrum Health Reference Laboratory, Grand Rapids, MI


Clot-based assay



CDM Code


Epic Test ID

Currently Unavailable


APTT: 14979-9

Mayo Access Code

Currently Unavailable

Reviewed Date