Coagulation laboratory tests

Coagulation laboratory tests - overview

Last author update: 1 June 2012
Last staff update: 4 March 2022

Copyright: 2002-2023,, Inc.

PubMed Search: Coagulation laboratory tests [title]

Jeremy C. Parsons, M.D.
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Cite this page: Parsons JC. Coagulation laboratory tests - overview. website. Accessed June 5th, 2023.
Definition / general
  • Performed in almost all hospitals in US
  • Necessary for diagnosis, treatment and management of bleeding and hypercoagulation disorders, to screen for coagulation disorders and to monitor anticoagulant therapy
  • CAP requires laboratories to notify medical staff immediately if a critical value is obtained
  • For critical values, CLIA requires laboratory to immediately alert individual or entity that requested the test, or if applicable, the individual responsible for using the test results
  • Tubes with 3.2% citrate are preferred over 3.8% citrate (higher concentration prolongs PT and PTT if tube not filled to the recommended level)
  • Do not draw specimens from indwelling catheters (which contain anticoagulants)
  • If multiple tubes are drawn, draw coagulation tube after the red top and before the EDTA, heparin or oxalate / fluoride tubes
  • Try to fill the sample tube completely
  • Notify laboratory if patient is on anticoagulants and specify which ones
  • Do not delay transport of tubes to laboratory; if delay cannot be avoided, separate plasma or serum from cells as soon as possible; store plasma (or serum) on ice for up to 4 hours, or store frozen
General algorithm
Bleeding tests
Clotting tests
Additional references
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