Hereditary bleeding disorders
Prekallikrein deficiency

Topic Completed: 1 October 2010

Revised: 4 April 2019, last major update October 2010

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Prekallikrein deficiency

Kendall Crookston, M.D., Ph.D.
Lizabeth S. Rosenbaum, M.D.
Page views in 2019: 402
Page views in 2020 to date: 367
Cite this page: Crookston K., Rosenbaum L., Gober-Wilcox J. Prekallikrein deficiency . website. Accessed August 12th, 2020.
Definition / general
  • Prekallikrein deficiency is a rare congenital disorder that causes an isolated prolonged PTT but is not associated with a bleeding tendency
  • Also known as Fletcher factor deficiency
  • Rare
  • 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
  • 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
  • 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)
  • Prolonged PTT that corrects after mixing study
  • Normal PT, thrombin time and bleeding time
  • Specific functional prekallikrein assay is diagnostic
Case reports
  • Typically not required
Differential diagnosis
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