How is the diagnosis of pulmonary alveolar proteinosis (PAP) confirmed?

Updated: Dec 18, 2019
  • Author: Rodolfo Laucirica, MD; Chief Editor: Philip T Cagle, MD  more...
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The diagnosis of PAP can be confirmed by various methods. In patients with autoimmune PAP, measurement of the autoantibody level against granulocyte macrophage colony-stimulating factor (GM-CFS) has been used to identify this disease. Using an enzyme-linked immunosorbent assay (ELISA)–based testing platform, Uchida and colleagues were able determine that a serum level of 5 ug/mL as the optimal cutoff value for distinguishing autoimmune PAP from normal serum. [32] Confirmation of PAP can also be obtained through examination of tissue specimens obtained by one of several methods. Previously, an open biopsy was considered the criterion standard to establish the diagnosis of PAP. However, transbronchial biopsies or cytologic evaluation of bronchoalveolar lavage (BAL) samples are now routinely used to diagnose this disease. [1, 6, 7, 33, 34, 35]

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