Hereditary bleeding disorders

Prekallikrein deficiency

Last author update: 1 October 2010
Last staff update: 23 September 2020

Copyright: 2002-2023,, Inc.

PubMed Search: Prekallikrein deficiency

Kendall Crookston, M.D., Ph.D.
Lizabeth S. (Rosenbaum) Marinaro, M.D.
Page views in 2022: 270
Page views in 2023 to date: 67
Cite this page: Crookston K, Rosenbaum LS, Gober-Wilcox J. Prekallikrein deficiency. website. Accessed April 1st, 2023.
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
Back to top
Image 01 Image 02