Question 19.3

The following results were obtained from a patient in the ICU


Patient Value

Adult Norma' Range

Prothrombin time

15.0 s

10.0 - 15.0

International normalised ratio (INR)


0.80 - 1.20

Activated Partial Thromboplastin Time (APTT)

40.8 s*

25.0 -35 0


2.0 g/L

2.0 —4.0

      a) List four possible causes.                                                                                         (20% marks)

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College answer

  • Anticoagulants – e.g. heparin
  • Lupus anticoagulant-type inhibitors 
  • Factor deficiencies – FXI, XII 
  • Artefactual


This  is somewhat unsatisfying, as no history is given other than the patient is in ICU.

In summary, the results are:

  • Normal PT; slightly elevated INR (1.2)
  • Slightly elevated APTT
  • Borderline low fibrinogen

Of these results the only actually abnormal one is the APTT.

Four possible causes of a slightly  raised APTT are:

  • Dilutional coagulopathy (as PT is also borderline)
  • Heparin therapy
  • Factors 8, 9 11 or 12 deficiency
  • von Willebrand's disease


Kamal, Arif H., Ayalew Tefferi, and Rajiv K. Pruthi. "How to interpret and pursue an abnormal prothrombin time, activated partial thromboplastin time, and bleeding time in adults." Mayo Clinic Proceedings. Vol. 82. No. 7. Elsevier, 2007.

DeMuro, J. P., and A. F. Hanna. "Trauma Induced Coagulopathy: Prevention and Intervention."Scand J Trauma Resusc Emerg Med 20.47 (2014): 4.

White, Julian. "Snake venoms and coagulopathy." Toxicon 45.8 (2005): 951-967.

Kashuk, Jeffry L., et al. "Primary fibrinolysis is integral in the pathogenesis of the acute coagulopathy of trauma." Annals of surgery 252.3 (2010): 434-444.

De Stefano, Valerio, Guido Finazzi, and Pier Mannuccio Mannucci. "Inherited thrombophilia: pathogenesis, clinical syndromes, and management [see comments]." Blood 87.9 (1996): 3531-3544.

Hunt, Beverley J. "Bleeding and coagulopathies in critical care." New England Journal of Medicine 370.9 (2014): 847-859.