Hamman-Rich syndrome laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Chandrakala Yannam, MD [2]

There are no diagnostic laboratory findings associated with acute interstitial pneumonitis. However, routine laboratory tests may help in identifying alternative diagnoses rather than making a diagnosis of acute interstitial pneumonitis, include abnormal arterial blood gases, physiologic lung testing, complete blood count, and sputum examination, and microbiologic tests.

Laboratory findings consistent with the diagnosis of acute interstitial pneumonitis include:

• Abnormal ABG
  • May indicate hypoxia, hypercapnia, and respiratory acidosis.
• Spirometry^[1]
  • May indicate a restrictive pulmonary disease.
  • A FEV1/FVC ratio > 80% indicates restrictive disease.
  • Peak flow assessment
    • May be below normal range which is 100 liters/minute for men, and 80 liters/minute for women.
• CBC
  • May indicate anemia, neutrophilia, elevated ESR, elevated CRP, and elevated immunoglobulin.
• Microbiologic tests:
  • Influenza testing using nasopharyngeal aspirates
  • Serologic tests for atypical pneumonias (eg, Coccidioides, Chlamydia, coronavirus)
  • Urinary antigen tests for Streptococcus pneumoniae and Legionella
• Serologic tests for detection of autoimmune diseases
• Abnormal sputum analysis
  • May contain bacteria, such as mycobacterium tuberculosis or inorganic particles, such as asbestos bodies or organic particles.
  • Pneumocystis jirovecii immunofluorescence

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