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Thrombin Time

Item Value
Approval req'd? No
Available Stat? Yes
Test code TT
Performed by Parnassus Hematology
In House Availability STAT: 24 hours, 7 days a week
ROUTINE: 0800 – 1600, 7 days a week
Collection Instructions Do not draw from heparin-containing lines.

1. Check the expiration date on the label of the blue top vacutainer before drawing the patient.

2. For blood collection in a sodium citrate blue top, the tube must be filled to above the Minimum Fill Indicator on the tube. It is crucial to wait and allow the tube to stop filling before removing it from the needle.

3. With use of a butterfly needle, draw about 1 cc using a separate blue top to remove air from tubing, discard the first tube and then draw a second blue top tube filled to the full extent of the vacuum.

4. Tubes should not be filled past the Maximum Fill dashed line by either using a syringe or removing the tube cap.

For patients with Hct's ≥ 55% please contact Hematology (For Parnassus patients call 3-1747, for Mission Bay patients call 6-0194) to obtain blue top tubes with adjusted citrate volumes in order to maintain the proper citrate to plasma ratio for coagulation studies.
Container type Blue top filled to full extent of vacuum
Amount to Collect 2.7 mL blood
Sample type Citrated plasma
Preferred volume 1 mL plasma
UCSF Rejection Criteria Samples collected in outdated blue top vacutainer. Over-filled or under-filled tubes may be rejected
Processing notes Test specimens within four hours of collection or freeze plasma in a plastic tube at -20C.
Units seconds
Normal range 21.6-30.1 sec
Turn around times Routine 24 hours, STAT 1 hour from receipt in Parnassus Laboratory
Additional information A prolonged thrombin time can be due to inhibitors of thrombin (for example, unfractionated heparin, direct thrombin inhibitors including argatroban and lepirudin, or paraneoplastic-associated heparinoid) or fibrinogen abnormalities (afibrinogenemia, hypofibrinogenemia, dysfibrinogenemia, anti-fibrinogen antibodies, or high fibrin split products).Correlation with fibrinogen level and clinical setting is suggested. Laboratory medicine resident can be reached by contacting the hematology lab at 353-1747.

If unusual findings are noted a pathologist review and interpretation may be performed and separately billed for

Thrombin time is performed at Parnassus Hematology. Samples from Mission Bay or Mt. Zion that are ordered routine will be sent to Parnassus on a routine courier. Please contact Mission Bay or Mt. Zion Hematology lab if a STAT thrombin time is ordered so that a STAT courier can be requested for delivery to Parnassus.
CPT coding 85670
LOINC code 3243-3
Last Updated 9/15/2017 5:30:09 PM
Entry Number 900
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