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Coagulation

Hereditary bleeding disorders

Prekallekrein deficiency


Reviewers: Kendall Crookston, M.D., Ph.D., University of New Mexico; Lizabeth Rosenbaum, MD, University of New Mexico; Julie Gober-Wilcox, M.D., Resident, University of New Mexico (see Reviewers page)
Revised: 6 October 2014, last major update October 2010
Copyright: (c) 2002-2014, PathologyOutlines.com, Inc.

Definition / General
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● Prekallikrein deficiency is a rare congenital disorder that causes an isolated prolonged PTT but is not associated with a bleeding tendency

Terminology
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● Also known as Fletcher factor deficiency

Epidemiology
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● Rare

Pathophysiology
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● Prekallikrein is a contact factor that complexes with high molecular weight kininogen and is cleaved by factor XII (Hageman factor) to produce kallikrein in the initial steps of the intrinsic pathway

Etiology
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● Autosomal recessive inheritance
● Homozygous individuals have <1% activity
● Heterozygous individuals have 20%-60% of normal activity
● There are rare variants of abnormal prekallikrein molecules

Clinical features
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● No bleeding tendency
● Usually detected in asymptomatic individuals after the incidental finding of isolated prolonged PTT
● There have been anecdotal reports of prekallikrein deficiency and increased risk of arterial and venous thrombosis, but usually thrombotic risk factors were identified (Acta Haematol 2010;123:210)

Laboratory
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● Prolonged PTT that corrects after mixing study
● Normal PT, thrombin time and bleeding time
● Specific functional prekallikrein assay is diagnostic

Case reports
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● Prekallikrein deficiency resulting in mucosal hemorrhage (Am J Med Sci 2009;338:429)

Treatment
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● Typically not required

Differential diagnosis
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Factor XII deficiency
High molecular weight kininogen deficiency
● Acquired prekallikrein deficiency due to DIC or liver disease, rarely due to antibodies to prekallikrein

Additional references
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Consultative Hemostasis and Thrombosis (2007)

End of Coagulation > Hereditary bleeding disorders > Prekallekrein deficiency


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