Prothrombin Time (PT), Plasma

Test Code

PT - NOCO

Alias/See Also

Protime
PT
INR

CPT Codes
85610

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

Instructions

The light blue capped tubes, containing 3.2% buffered sodium citrate, used for coagulation testing must be allowed to fill completely (after filling a small air space will normally be present). For patients having a hematocrit greater than 55%, contact the hospital coagulation department to obtain a special collection tube.

Specimen Stability

Unopened collection tube < 24 hours

Opened collection tube < 4 hours

If testing is not completed within above time frames transfer plasma to plastic tube using a plastic transfer pipette. Freeze at -20°C. Frozen plasma is stable for 2 weeks at -20°C.

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

Clotted
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Drawn in outdated/expired tube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

Methodology

Setup Schedule

Monday through Sunday; Continuously

Report Available

Daily

Reference Range

Refer to the Coagulation Reference Range and Critical Results documents in the Resources file on the facility test directory page.

Performing Laboratory
Banner Fort Collins Medical Center Laboratory
North Colorado Medical Center Laboratory

Last Updated: August 13, 2026

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.