Test Code LAB324 Thrombin Time, Plasma
Methodology
Absorbance measurement, Clot signature formation
Testing Algorithm:
If thrombin time is >25 seconds, the test is repeated with
protamine sulfate added to confirm or rule out the presence of
heparin, at an additional charge.
Literature References:
Package insert: HemosIL Thrombin Time (pn9758515)
determination by the ACL TOP, Instrumentation Laboratory,
12/2016
Performing Laboratory
Barnes-Jewish Hospital Laboratory
Specimen Requirements
Specimen Type: Plasma
Container/Tube: Light-blue top (citrate)
Specimen Volume: Full tube
Specimen Minimum Volume: Full tube
Collection Instructions:
- Draw a discard blue top tube prior to drawing a light-blue top (citrated) tube if using a Winged Infusion Set. Discard tube should be under filled and discarded.
- Clotted blood or an insufficient specimen is not acceptable.
- Avoid phlebotomy techniques which cause hemolysis and heparin contamination.
- Follow nursing policy on volume of blood to discard prior to collecting blood from indwelling heparinized catheters.
Analyte Stability:
Nonheparinized:
24 hours at 2° C to 24° C.
Platelet-free plasma can be frozen at -20 for transport on dry
ice up to 72 hours
or stored 6 months at -70° C.
Heparin therapy:
2 hours at 18° C to 24° C.
Platelet-free plasma
can be frozen at -20 for transport on dry ice up to 72 hours
or stored 6 months at -70° C.
Additional Information: If the patient is a hospital patient and the hematocrit is >55%, call Barnes-Jewish Hematology Laboratory at 314-362-5203 for instructions.
Specimen Transport Temperature
Ambient Yes/Refrigerate NO/Frozen Yes
Reference Values
10-15 seconds
Confirmation results appear in the report as thrombin
time-protamine corrected.
Physician alert value (automatic call-back): >30 seconds on
correction
Day(s) Test Set Up
Monday through Sunday
Turnaround Time:
STAT: 1 hour after receipt in laboratory
Routine: 2-4 hours after receipt in laboratory
Test Classification and CPT Coding
85670-Thrombin time, plasma
85670-Confirmation (if appropriate)
Additional Information
For BJH Laboratory Use Only
Analyte Stability:
Nonheparinized:
24 hours at 2° C to 24° C.
Heparin therapy:
2 hours at 18° C to 24° C.
Heparin and Non-heparinized:
Platelet-free plasma
can be frozen at -20 for transport on dry ice up to 72 hours
or stored 6 months at -70° C.
Laboratory Processing Instructions:
Test performed in BJH Hematology.
LOINC Code Information
Name | LOINC Code |
Thrombin Time, Plasma | 3243-3 |
Thrombin Time, Protamine Corrected | 33673-5 |