Coagulation
Coagulation laboratory tests
Abnormal PT and PTT - causes

Author: Jeremy Parsons, M.D. (see Authors page)

Revised: 5 May 2016, last major update June 2012

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

PubMed Search: Abnormal PT and PTT - causes

Table of Contents
Definition / General
Cite this page: Abnormal PT and PTT - causes. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/coagulationabnormalPTPTT.html. Accessed December 9th, 2016.
Definition / General
  • PT normal, PTT prolonged:
    • Deficiency of intrinsic pathway factors VIII, IX, XI, XII
    • Less commonly prekallikrein or high molecular weight kininogen
    • Also prolonged delay in transporting specimen to lab (affects factors V and VIII), presence of heparin in specimen

  • PT prolonged, PTT normal:
    • Deficiency of extrinsic pathway factor VII
    • Occasionally due to deficiency of common pathway factors fibrinogen, prothrombin, factors V or X, early Vitamin K deficiency (dietary or warfarin)

  • PT and PTT prolonged:
    • Deficiency of common pathway factors fibrinogen, prothrombin, factors V or X, or multiple factor deficiencies