Prothrombin Time (PT, INR)

Cleveland HeartLab P, Test

CPT Code: 85610
Order Code: C2440
ABN Requirement: No
Synonym: PT; INR
Specimen: Sodium Citrate Plasma
Volume:  1.0 mL
Minimum Volume:  0.5 mL
Container: Sodium citrate (Light Blue top) tube


Sodium Citrate Plasma:

  1. Draw a full tube and gently invert 3 to 4 times.
  2. Centrifuge for 10 minutes.
  3. Pre-squeeze transfer pipet bulb and draw off approximately 2/3 of the upper plasma layer.
    Note: This ensures that the buffy coat and red cells remain undisturbed.
  4. Aliquot plasma into labeled transport tube and cap tightly. Discard original tube.
  5. Store transport tube frozen at -20°C until ready to ship.

Transport: Store plasma at -20°C after collection and ship the same day per packaging instructions provided with the Cleveland HeartLab shipping box.

  • Please note: Ship frozen sodium citrate plasma on dry ice.

Special Information: Sodium citrate collection tube must be filled to total fill volume.


Ambient (15-25°C): 24 hours
Refrigerated (2-8°C):
Frozen (-20°C):
14 days
Deep Frozen (-70°C):
6 months

Causes for Rejection: Specimens other than sodium citrate plasma; improper labeling; samples not stored properly; samples older than stability limits; samples received not frozen

Methodology: Automated Optical Clot Detection

Turn Around Time: 2-3 days

Reference Range:

Prothrombin Time0-1 days7.9-14.8
2-5 days7.4-14.2
6-30 days7.2-13.3
1-3 months7.2-13.2
4-11 months8.3-12.9
1-99 years8.4-13.0
INR0-1 days0.7-1.4
2-5 days0.7-1.3
6-30 days0.7-1.2
1-3 months0.7-1.2
4-11 months0.8-1.2
1-99 years0.8-1.2

Urgent Range:

INRAll Ages>5.0

Intended Use: Evaluation of hemostasis.

Clinical Significance: Recommended Therapeutic Ranges for Oral Anticoagulant use (INR = International Normalized Ratio):

  • INR 2.0-3.0: Prevention of venous thrombosis, recurrent DVT, stroke and embolism with tissue heart valves, treatment of venous thrombosis, PE, TIA, atrial fibrillation, and post-myocardial infarction.
  • INR 2.5-3.5: Prevention of embolism with mechanical heart valves or lupus anticoagulant.
  • INR 3.0-4.5: For reduced recurrence/mortality from stroke and myocardial infarction.

The CPT codes provided 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 payer being billed.