Last reviewed: 6 Apr 2021
Last updated: 24 Mar 2020



History and exam

Key diagnostic factors

  • presence of risk factors
  • flu-like illness with low-grade fever, fatigue, and arthralgia

Other diagnostic factors

  • cough
  • shortness of breath
  • bilateral crackles

Risk factors

  • infectious pneumonia
  • connective tissue diseases
  • immunological diseases and inflammatory bowel disease
  • organ transplantation
  • medication use
  • breast radiotherapy
  • exposure to toxins

Diagnostic investigations

1st investigations to order

  • CXR
  • high-resolution chest CT scan (HRCT)
  • FBC
  • erythrocyte sedimentation rate

Investigations to consider

  • pulmonary function tests
  • video-assisted thoracoscopic biopsy
  • creatine kinaseĀ 
  • anticardiolipin antibodies
  • lupus anticoagulant antibodies

Treatment algorithm


Gary R. Epler

Clinical Associate Professor

Harvard Medical School




GRE is an author of several references cited in this topic.

Peer reviewersVIEW ALL

Professor of Medicine and Director

Division of Pulmonary/Critical Care/Allergy/Sleep Medicine

Medical University of South Carolina




SS declares that he has no competing interests.

National Jewish Medical and Research Center




TLC has been reimbursed by the American College of Chest Physicians (ACCP), American Academy of Sleep Medicine, American Thoracic Society, and Cephalon, the manufacturer of modafinil, for attending several conferences. He has been paid by the ACCP for running educational programs and by Elsevier for serving as consultant of the Sleep Medicine Clinics. He has also received research funding from the National Institutes of Health, Respironics, Restore, and Schwarz Pharma, and has been a member of the speakers' bureau for GlaxoSmithKline.

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