Coagulation laboratory tests
Reviewer: Jeremy Parsons, M.D. (see Reviewers page)
Revised: 10 Feburary 2013, last major update November 2012
Copyright: (c) 2002-2013, PathologyOutlines.com, Inc.
● Prekallikrein is also known as Fletcher factor
● Screening assays: preincubate PTT sample for 10 minutes prior to adding calcium; a prolonged PTT that shortens after the 10 minute preincubation is suspicious for prekallikrein deficiency
● PTT performed with elagic acid as the intrinsic pathway activator will be normal in prekallikrein deficiency
● Specific assay: preincubate patient plasma with prekallikrein-deficient plasma for 1 minute, then add calcium and perform PTT; prekallikrein level is determined from a standard curve of prekallikrein vs. PTT (Thromb Res 2002;105:463)
● Interference is due to hirudin, argatroban, danaparoid and heparin (add heparinase)
● Reference range is 60-140% of normal; newborn levels are lower, but increase to near adult levels by age 6 months
● Indications: prolonged PTT corrected with mixing study, factors VIII, IX, XI and XII are normal, PT and fibrinogen are normal, lupus anticoagulant assays are negative
End of Coagulation > Coagulation laboratory tests > Prekallikrein assay
This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.
All information on this website is protected by copyright of PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.com with any questions (click here for other contact information).