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EPIC CODE: LAB324 Thrombin Time (Bovine), Plasma

Additional Codes

Sunquest:  TTM
Mayo:         TTSC

Specimen Required

Patient Preparation: Fasting preferred

Collection Container/Tube: Light-blue top (3.2% sodium citrate)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing in Special Instructions.

2. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.

3. Aliquot plasma into a separate plastic vial leaving 0.25 mL in the bottom of centrifuged vial.

4. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally, ≤-40° C.

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.


If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.

Secondary ID


Useful For

Detecting or excluding the presence of heparin or heparin-like anticoagulants (which act by enhancing antithrombin's inhibition of thrombin and other procoagulant enzymes) when used in conjunction with the reptilase time (RT) in evaluating unexplained prolonged clotting times


Identifying the cause of a prolonged prothrombin time, activated partial thromboplastin time, or dilute Russell viper venom time when used in conjunction with the RT and fibrinogen assay

Method Name

Optical Clot-Based

Reporting Name

Thrombin Time (Bovine), P

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 14 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Clinical Information

Prolonged clotting times may be associated with a wide variety of coagulation abnormalities including:

-Deficiency or functional abnormality (congenital or acquired) of many of the coagulation proteins

-Deficiency or functional abnormality of platelets

-Specific factor inhibitors

-Acute disseminated intravascular coagulation

-Exogenous anticoagulants (eg, heparin, warfarin)


The prothrombin time and activated partial thromboplastin time are first-order tests for coagulation abnormalities and are prolonged in many disorders. A battery of coagulation tests is often required to determine the cause of prolonged clotting times.


Thrombin catalyzes the transformation of fibrinogen to fibrin (by cleaving fibrinopeptides A and B), which is followed by polymerization of fibrin to form a clot. The thrombin time (TT) test measures the time of clot formation when thrombin is added to citrated plasma. The phospholipid-dependent procoagulant enzyme cascades (intrinsic, extrinsic, and "common" pathway) are bypassed by the addition of exogenous thrombin. Therefore, the TT mainly reflects functions and interactions of solution-phase exogenous thrombin and endogenous fibrinogen.

Reference Values

15.8-24.9 seconds


Prolongation of the thrombin time (TT) is consistent with the presence of heparin-like anticoagulants, hypofibrinogenemia, dysfibrinogenemia, fibrin degradation products, and antibody inhibitors of thrombin. An immeasurably prolonged TT is usually the result of heparin in the specimen or, rarely, the presence of thrombin antibodies or afibrinogenemia.


When the TT test is performed with diluted bovine thrombin to achieve a normal plasma clotting time of about 20 seconds, the TT is capable of detecting unfractionated heparin at a concentration of 0.05 units/mL of heparin.


Other tests useful in interpreting the significance of prolongation of the TT include: reptilase time (RT), human thrombin time, clottable fibrinogen assay, and the fibrin D-dimer assay. These tests are available as components of coagulation profile test panels. As seen in the following table, RT can help distinguish among the various causes of a prolonged TT.


Thrombin time

Reptilase time





Hypo- or afibrinogenemia

Ascertain by determination of fibrinogen




Ascertain by specific assay



Heparin or inhibitor of thrombin

Differentiate by human TT and/or heparin assays



Fibrin(ogen) split products (FSP)

Ascertain by FSP or D-dimer assay


Note: Rare congenital dysfibrinogenemias associated with venous thromboembolism (eg, fibrinogen Bordeaux) may demonstrate normal thrombin and reptilase times and normal Clauss fibrinogen levels.


The thrombin time test, by itself, has little diagnostic value and should be interpreted within the context of additional coagulation assays (eg, prothrombin time, activated partial thromboplastin time, and reptilase time).

Clinical Reference

1. Koepke JA: Coagulation testing systems. In: Practical Laboratory Hematology. Churchill Livingston; 1991

2. Corriveau DM, Fritsma G: Hemostasis and Thrombosis in the Clinical Laboratory. JB Lippincott Company; 1988

3. Galanakis DK: Plasma thrombin time and related tests. In: Williams Hematology. 5th ed. McGraw-Hill Book Company; 1995:L91-L93

4. Greaves M, Preston FE: Approach to the bleeding patient. In: Colman RW, Hirsh J, Marder VJ, et al. eds. Hemostasis and Thrombosis: Basic Principles and Clinical Practice. 4th ed. JB Lippincott Company; 2001:783-837

5. Turgeon TL, ed: Clinical Hematology. 6th ed. Wolkers Kluer and Co; 2018

Method Description

The thrombin time (TT) assay is performed on the Instrumentation Laboratory ACL TOP. Patient plasma is combined with a bovine thrombin reagent containing bovine albumin, calcium chloride, and buffer immediately triggering the coagulation process in the mixture. Time to clot formation is measured optically using a wavelength of 405 nm.(Package insert: HemosIL Thrombin Time, IL TOP Operators Manual. Instrumentation Laboratory Company; 06/2017)

Day(s) Performed

Monday through Saturday

Report Available

1 to 4 days

Specimen Retention Time

7 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
TTSC Thrombin Time (Bovine), P 46717-5


Result ID Test Result Name Result LOINC Value
TTSC Thrombin Time (Bovine), P 46717-5

NY State Approved