A Distinguishing Feature

Sanjiv J. Shah*, Aubrey O. Ingraham, Sandra Y. Chung, Richard J. Haber

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter


This chapter presents the case study of a patient with a history of chronic liver disease of unknown etiology. The case study illustrates the importance, as the key to diagnosis, of determining a "distinguishing feature" such as a prolonged activated partial thromboplastin time (aPTT) from among the multitude of abnormalities that could have led the diagnostic process astray. Whereas faulty use of trigger features may make physicians inappropriately consider uncommon diseases, a "distinguishing feature" limits the number of diagnostic possibilities and significantly changes-increases or decreases-the likelihood of there being a rare disease. By correctly using the distinguishing feature of an elevated aPTT in the context of the patient's diverse clinical features, the discussant was able to arrive at a single unifying diagnosis of antiphospholipid syndrome.

Original languageEnglish (US)
Title of host publicationClinical Care Conundrums
Subtitle of host publicationChallenging Diagnoses in Hospital Medicine
PublisherJohn Wiley and Sons
Number of pages8
ISBN (Print)9780470905654
StatePublished - Mar 21 2013


  • Activated partial thromboplastin time (aPTT)
  • Adrenal insufficiency
  • Antiphospholipid syndrome
  • Chronic liver disease
  • Hypercoagulability
  • Thrombosis

ASJC Scopus subject areas

  • Medicine(all)

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