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Test Code
PTPR
Test Name
Prothrombin Time Mixing Study
CPT Codes
85610
Included Tests
  • Prothrombin Time
  • International Normalized Ratio (INR)

Reflexed when appropriate:

  • Thrombin Time
  • Reptilase Time
  • Prothrombin Time Mixing Study
Expected Turnaround Time
1 - 4 days
Clinical Utility

Distinguish between circulating inhibitor and coagulation factor deficiency when the prothrombin time (PT) is prolonged.
Specimen and Container Info

Specimen Type: Plasma  

Collection Container: 2 Full Light Blue Top (Sodium Citrate) 
Collection Instructions

Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.

Processing and Submission Instructions

Create platelet poor plasma according to the Specimen Collection and Processing Guidelines for Coagulation Testing.

Patient Preparation
Testing is contradictory for patients on anticoagulant therapy.
Transport Instructions
  • Inpatient: Transport to the laboratory at room temperature.
  • Outpatient: Transport to the laboratory frozen. 
Stability Requirements

Room Temperature

4 hours

Frozen

Platelet poor plasma: 14 days
Causes for Rejection
  • Clotted specimen
  • Specimen past stability
  • Specimen not properly filled
  • Specimen thawed in transit
Methodology
Mechanical Clot Detection
Reference Intervals

See Indvidual Test Listings.
Performing Location
Roble Road Core Laboratory
Alternate Names
  • PT Mixing Study
Testing Schedule
Routine, Monday - Friday no holidays
The American Medical Association (AMA) Current Procedural Terminology (CPT) codes published by HNL Lab Medicine are guidelines and are intended for informational purposes only. CPT coding is the exclusive responsibility of the billing entity. View the Terms.
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