Detecting and Evaluating Coagulation Inhibitors and Factor Deficiencies

Author: Leah Coppolino, MPH, CLS(NCA), MT(ASCP)
Reviewer: Donna D. Castellone, MS, MT(ASCP)SH and Laurie Bjerklie, MA, MLS(ASCP)CM
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Continuing Education Credits

P.A.C.E.® Contact Hours: 1 hour(s)

Florida Board of Clinical Laboratory Science CE Credit Hours

Florida Board of Clinical Laboratory Science CE - General (Hematology): 1 hour(s)

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What causes a patient's prothrombin time and/or activated partial thromboplastin time to be prolonged when the patient is not on anticoagulant therapy? Is it something that happened as a result of the collection process, is it related to an illness, or is it perhaps related to a factor deficiency or a circulating coagulation inhibitor? This course will acquaint you with several conditions associated with prolonged PT and aPTT test results. You will learn when it is appropriate to perform a mixing study, whether the results suggest a factor deficiency or a coagulation inhibitor, and further testing that can be done to confirm your results.

Objectives

  • Determine various causes of an elevated prothrombin time or activated partial thromboplastin time result.
  • Evaluate situations in which performing a mixing study would be appropriate.
  • List the steps involved in a prothrombin time or activated partial thromboplastin time mixing study procedure.
  • Analyze and interpret mixing study results to distinguish a factor deficiency from a circulating inhibitor.
  • Determine which, if any, further coagulation studies would prove helpful after obtaining mixing study results.

Course Outline

  • Introduction to Coagulation Inhibitors and Factor Deficiencies
    • Introduction to Coagulation Inhibitors
    • Coagulation Inhibitors
    • Introduction to Factor Deficiencies
    • Coagulation Inhibitors and Coagulation Screening Tests
  • Evaluating Prolonged Test Results
    • Coagulation Factors Monitored by the Prothrombin Time Test
    • Coagulation Factors Involved in the Activated Partial Thromboplastin Time Test
    • Elevations in PT or aPTT Assays
    • Pre-examination Variables Causing Falsely Elevated Results
    • Summary of Initial Elevations in the PT and aPTT
    • Which of the following may produce a falsely prolonged aPTT test result?
    • True or False: Performing a thrombin time to detect heparin contamination in a patient's plasma is done to avoid performing mixing studies for aPTTs that would result in a false positive result.
  • Performing a Mixing Study
    • Introduction to Mixing Studies
    • When to Perform a Mixing Study
    • Mixing studies may help to determine the presence of which of the following?
    • Mixing Study Test Principle
    • Mixing Study Specimen Requirements
    • Performance of a Mixing Study
    • Performance of a Mixing Study, continued
    • Performance of a Mixing Study, continued
    • What is the ratio of patient plasma to pooled normal plasma that is usually used in the performance of a mixing study?
    • What is the minimum percentage of each coagulation factor that must be present in a patient's plasma to produce a normal PT and aPTT test result?
  • Analyzing and Interpreting Mixing Study Results
    • Analyzing the Mixing Study Results
    • Interpreting the Mixing Study Results
    • Are the patient's mixing study results corrected or not corrected? Would this support the presence of a factor deficiency or coagulation inhibitor?Initial PTImmediate Mixing Study PTIncubated Mixing Study PT23 sec. 12 sec. 13 sec.
    • Analyzing the Mixing Study Results, continued
    • Analyzing the Mixing Study Results, continued
    • Mixing Study Methodology Differences
  • Case Study One
    • Case Study One
    • Case Study One, continued
    • After reviewing the mixing study results, what is the most likely determination?
    • Which factor level could be deficient?
  • Case Study Two
    • Case Study Two
    • After reviewing the mixing study results, is the aPTT corrected or not corrected? Does this support the presence of a factor deficiency or coagulation inhibitor?
  • Case Study Three
    • Case Study Three
    • Has the mixing study corrected the aPTT? Is a factor deficiency or a coagulation inhibitor the likely cause of the patient's prolonged aPTT?
  • Determination of Further Coagulation Studies
    • Further Analyses for Factor Deficiencies
    • Further Analyses for Factor Deficiencies, continued
    • Factor Activity Curves
    • Treatment for Factor Deficiencies
    • Lupus Anticoagulant
    • Lupus Anticoagulant, continued
    • Further Analyses for Coagulation Inhibitors
    • Treatment for Coagulation Inhibitors
    • Which of the following tests is used to quantify a coagulation inhibitor?
  • References
    • References

Additional Information

Level of Instruction: Intermediate
Intended Audience: Medical laboratory scientists and technicians. This course is also appropriate for medical laboratory science and technician students and pathology residents.
Author Information: Leah Coppolino, MPH, CLS(NCA), MLS(ASCP) is the Director of the Clinical Laboratory Science Program at St. Christopher’s Hospital for Children in Philadelphia, Pennsylvania. She holds a Masters in Public Health from Thomas Jefferson University.
Reviewer Information:
Donna D. Castellone, MS, MLS(ASCP)SH has worked as a coagulation specialist in both clinical and commercial settings. Ms. Castellone holds a Masters's Degree in Health Science and Administration from State University at Stony Brook, Stony Brook, New York. She has written over 70 articles, was a contributing author for three textbooks, and is a frequent lecturer at laboratory workshops.
Laurie Bjerklie, MA, MLS(ASCP)CM, is currently an Education Developer for MediaLab and LabCE. She earned a B.S. in Medical Laboratory Science from the University of North Dakota and an M.A. in Curriculum and Instruction from Saint Xavier University. She has over 15 years of experience in higher education and has held program director and faculty positions in both MLT and MLS programs
Course Description: Prolonged PT and aPTT results are caused by many different conditions. It is important for medical laboratory scientists to be able to distinguish between preanalytic causes, secondary clinical causes, and important and potentially dangerous causes such as coagulation factor deficiencies and circulating coagulation factor inhibitors. Upon completion of this course, you will be able to identify the common causes associated with prolonged PT and/or aPTT results, when it is appropriate to perform a mixing study, how to perform and interpret mixing studies, how to differentiate between factor deficiencies and factor inhibitors, and further testing that can be done to confirm mixing study results.