Thrombin time

<h2 id="test-procedure">Test procedure</h2>
<p>After separating the plasma from the whole blood by <a href="/facts/Centrifugation/q9WkB8T4">centrifugation</a>, bovine <a href="/facts/Thrombin/sU9x3MeH">thrombin</a> is added to the sample of plasma. Clot formation is detected optically or mechanically by a coagulation instrument. The time between the addition of the thrombin and the clot formation is recorded as the thrombin clotting time.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a>
</p>
<h2 id="specimen-requirements">Specimen requirements</h2>
<p>Whole blood is taken with either <a href="/facts/Citrate/EgKGQBdl">citrate</a> or <a href="/facts/Oxalate/u0Gdem0A">oxalate</a> additive (if using the <a href="/facts/Vacutainer/1NEAg7xm">vacutainer</a> system, this is a light blue top tube).  As with other coagulation assays, the tube must not be over- or under-filled in order to ensure the correct anticoagulant-to-blood ratio: one part anticoagulant per nine parts blood.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a>
</p>
<h2 id="reference-ranges">Reference ranges</h2>
<p>The <a href="/facts/Reference_interval/IqNt7ELQ">reference ranges</a> of the thrombin clotting time is generally <22 seconds,<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> and often from 14 to 16 seconds.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> Laboratories usually calculate their own ranges, based on the method used and the results obtained from healthy individuals from the local population.  Variability arises from differences in thrombin concentration, dilution of plasma, presence and/or concentration of calcium ions, as well as the influence of analyser type.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> TT may also be sensitive to citrate pH. Separate ranges are used for infants.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a>
</p>
<h2 id="limitations">Limitations</h2>
<p>Blood samples that are more than eight hours old can give inaccurate results when tested.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a>
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Coagulation_cascade/vnfEevM0">Coagulation cascade</a></li>
<li><a href="/facts/Partial_thromboplastin_time/vLzYoHoh">Partial thromboplastin time</a> (PTT), or activated partial thromboplastin time (aPTT or APTT)</li>
<li><a href="/facts/Prothrombin_time/pkLRGqcY">Prothrombin time</a> (PT)</li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="http://www.fpnotebook.com/hemeonc/lab/ThrmbnTm.htm">http://www.fpnotebook.com/hemeonc/lab/ThrmbnTm.htm</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>David Lillicrap; Nigel Key; Michael Makris; Denise O'Shaughnessy (2009). Practical Hemostasis and Thrombosis. Wiley-Blackwell. p. 53. ISBN 978-1-4051-8460-1. <a href="978-1-4051-8460-1" target="_blank">978-1-4051-8460-1</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Popović M, Smiljanić K, Dobutović B, Syrovets T, Simmet T, Isenović ER (January 2012). "Thrombin and vascular inflammation". Molecular and Cellular Biochemistry. 359 (1–2): 301–13. doi:10.1007/s11010-011-1024-x. PMID 21858738. S2CID 14313728. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Hatton, Chris (2008). Haematology (Lecture Notes). Cambridge, MA: Blackwell Publishers. p. 156. ISBN 978-1-4051-8050-4. <a href="978-1-4051-8050-4" target="_blank">978-1-4051-8050-4</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Batroxobin factsheet <a href="http://www.american-diagnostica.de/fileadmin/user_upload/datasheets/520REG.pdf" target="_blank">http://www.american-diagnostica.de/fileadmin/user_upload/datasheets/520REG.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>David Lillicrap; Nigel Key; Michael Makris; Denise O'Shaughnessy (2009). Practical Hemostasis and Thrombosis. Wiley-Blackwell. p. 53. ISBN 978-1-4051-8460-1. <a href="978-1-4051-8460-1" target="_blank">978-1-4051-8460-1</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>Mackie I, Casini A, Pieters M, Pruthi R, Reilly-Stitt C, Suzuki A. International council for standardisation in haematology recommendations on fibrinogen assays, thrombin clotting time and related tests in the investigation of bleeding disorders. Int J Lab Hematol. 2024 Feb;46(1):20-32. doi: 10.1111/ijlh.14201. Epub 2023 Nov 20. PMID: 37984807. <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>Hoffbrand, A. V. (2002). Essential haematology. Oxford: Blackwell Science. p. 248. ISBN 978-0-632-05153-3. <a href="978-0-632-05153-3" target="_blank">978-0-632-05153-3</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>Mackie I, Casini A, Pieters M, Pruthi R, Reilly-Stitt C, Suzuki A. International council for standardisation in haematology recommendations on fibrinogen assays, thrombin clotting time and related tests in the investigation of bleeding disorders. Int J Lab Hematol. 2024 Feb;46(1):20-32. doi: 10.1111/ijlh.14201. Epub 2023 Nov 20. PMID: 37984807. <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
<li id="fn:9"><p>Mackie I, Casini A, Pieters M, Pruthi R, Reilly-Stitt C, Suzuki A. International council for standardisation in haematology recommendations on fibrinogen assays, thrombin clotting time and related tests in the investigation of bleeding disorders. Int J Lab Hematol. 2024 Feb;46(1):20-32. doi: 10.1111/ijlh.14201. Epub 2023 Nov 20. PMID: 37984807. <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li>
<li id="fn:10"><p>Mackie I, Casini A, Pieters M, Pruthi R, Reilly-Stitt C, Suzuki A. International council for standardisation in haematology recommendations on fibrinogen assays, thrombin clotting time and related tests in the investigation of bleeding disorders. Int J Lab Hematol. 2024 Feb;46(1):20-32. doi: 10.1111/ijlh.14201. Epub 2023 Nov 20. PMID: 37984807. <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li>
<li id="fn:11"><p>Gastineau DA, Gertz MA, Daniels TM, Kyle RA, Bowie EJ (June 1991). "Inhibitor of the thrombin time in systemic amyloidosis: a common coagulation abnormality". Blood. 77 (12): 2637–40. doi:10.1182/blood.V77.12.2637.2637. PMID 1904284. <a href="http://www.bloodjournal.org/cgi/pmidlookup?view=long&pmid=1904284" target="_blank">http://www.bloodjournal.org/cgi/pmidlookup?view=long&pmid=1904284</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li>
<li id="fn:12"><p>Hoffbrand, A. V. (2002). Essential haematology. Oxford: Blackwell Science. p. 248. ISBN 978-0-632-05153-3. <a href="978-0-632-05153-3" target="_blank">978-0-632-05153-3</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li>
<li id="fn:13"><p>Mackie I, Casini A, Pieters M, Pruthi R, Reilly-Stitt C, Suzuki A. International council for standardisation in haematology recommendations on fibrinogen assays, thrombin clotting time and related tests in the investigation of bleeding disorders. Int J Lab Hematol. 2024 Feb;46(1):20-32. doi: 10.1111/ijlh.14201. Epub 2023 Nov 20. PMID: 37984807. <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li>
<li id="fn:14"><p>"Screening Tests in Haemostasis: The Prothrombin Time [PT]". practical-haemostasis.com. <a href="https://practical-haemostasis.com/Screening%20Tests/pt.html" target="_blank">https://practical-haemostasis.com/Screening%20Tests/pt.html</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li>
<li id="fn:15"><p>Heil W, Grunewald R, Amend M, Heins M (June 1998). "Influence of time and temperature on coagulation analytes in stored plasma". Clinical Chemistry and Laboratory Medicine. 36 (7): 459–62. doi:10.1515/CCLM.1998.077. PMID 9746270. S2CID 23594097. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li>
</ol>

Thrombin time open-in-new

Thrombin time