Activated Partial Thromboplastin Time (APTT), Plasma

See specimen stability for guidance when drawing specimens at a location other than McKee Medical Center, North Colorado Medical Center, Banner Fort Collins Medical Center, Sterling Regional Medical Center, or East Morgan County Hospital. STAT courier must be called for transport to the performing laboratory when stability is less than 24 hours. 

Test Code

CPT Codes

Preferred Specimen
1.0 mL plasma from Blue Top (Na Citrate)

Patient Preparation
  • The patient's heparin drip should be paused for 1-5 minutes prior to collection, but should not exceed 5 minutes.
  • Only use a discard tube if using a butterfly for specimen collection, then discard the first 3-5mL.

Minimum Volume
Full blue top tube or 1.0 mL plasma frozen
Note: For neonate requirements see Neonate Minimum Blood Volumes

  • It is imperative that the tube be completely filled to frosted line. The ratio of blood to anticoagulant is critical for valid coagulation results. If obtaining blood with a syringe, fill the light blue-top (sodium citrate) tube first.
  • If patient is on heparin, specimen must be centrifuged and separated within 1 hour of draw.
  • Heparin contaminated tube is not acceptable.
  • Keep specimen anaerobic.
  • Patients with an extremely high hematocrit may require special tubes before obtaining blood for coagulation testing. Please contact the lab for further information.
  • If testing will not be completed within 4 hours, spin down, remove plasma, and spin plasma again, and send specimen frozen in plastic vial.

Specimen Stability
Specimen Type Temperature Time
Whole blood Na Cit  on heparin Ambient 1 hour
Whole blood Na Cit (unopen/unspun) Ambient 4 hours
Plasma Na Cit (open/spun) Ambient 4 hours
Plasma Na Cit double spun and separated Frozen -20 C 2 weeks

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Serum received instead of Sodium Citrate plasma

Specimen past stability

Frozen plasma received thawed

Underfilled or Overfilled, blood/anticoagulant ratio must be 9/1; specimens must be between 90% -110% full

Collected in a 3.8% Sodium Citrate tube instead of 3.2% Sodium Citrate tube

Drawn in outdated/expired tube

HCT > 55%

Hemolyzed, icteric, or lipemic sample
Samples received on ice

Automated Clot Lysis

Setup Schedule
Monday through Sunday; Continuously

Report Available
Same day

Reference Range

Clinical Significance
Prolonged clotting times may be observed in the following situations: deficiency of Factors II, V, VIII, IX, X, XI, XII or fibrinogen, liver diseases, Vitamin K deficiency, presence of heparin, lupus anticoagulant or another inhibitor. 

Performing Laboratory
Banner Fort Collins Medical Center Laboratory
McKee Medical Center Laboratory
North Colorado Medical Center Laboratory
Summit View Laboratory
Sterling Regional Medical Center
East Morgan County Hospital

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.