Test directory: Prothrombin Time (PT)

Ordering Code514
Test NameProthrombin Time (PT)
Preferred SpecimenWhole Blood
Preferred ContainerCitrate, 3.2% (Lt Blue)
Other Specimen/ContainerPlasma in Citrate, 3.2% (Lt Blue)
Optimum VolumeWhole Blood: Entire tube
Plasma: 1.0 mL
Collection InstructionsDraw full tube
Mix tube well.
Handling InstructionsDo NOT chill whole blood - results may be affected
Double centrifuge plasma, separate, and freeze at -20 deg. C immediately. Do NOT thaw once specimen is frozen.
Transport RequirementsOn Oahu: Ambient if Whole Blood and testing is done
within 24 hours
Airline: Frozen (Plasma)
Note: Send Frozen Plasma if testing will be done >24 hours
from collection
Specimen StabilityAmbient: 24 hours (Unopened/Untested Master tube)
Ambient: 4 hours (Aliquoted Plasma, Opened tube)
Refrigerated: Not Stable
Frozen: 2 weeks Plasma
Rejection CriteriaClotted, Contaminated, Hemolyzed, Overfilled tube, Specimen older than stability limits, Underfilled tube, Add-on to previously tested specimen >4 hours
Avail. StatYES
Analytic Time1 Day
MethodologyClot Detection

Reference range(s)

ComponentAgeMale NormMale Critical LowMale Critical HighFemale NormFemale Critical HighFemale Critical LowUnitsAdd'l info
INRALL>= 4.5>= 4.5
Moderate-intensity... Moderate-intensity Warfarin therapy         2.0-3.0
Higher-intensity Warfarin therapy           2.5-3.5