How is pulmonary alveolar proteinosis (PAP) diagnosed?

If your doctor suspects PAP, he or she will first examine you. If you have PAP, your doctor might hear a crackling sound when he listens to your lungs. Other tests are likely, including:

  • Blood tests, including those that measure gas levels in your blood
  • Pulmonary function tests that measure how well your lungs are working
  • Imaging tests, including chest X-rays or high resolution computed tomography (HRCT) scans
  • Bronchoscopy, a test that uses a thin scope to look into your airways
  • Transbronchial biopsy, a less invasive way of using a bronchoscope to test tissue or fluid from the lungs for further testing
  • Open surgical lung biopsy, a test that removes tissue from the lungs to examine under a microscope

Last reviewed by a Cleveland Clinic medical professional on 06/06/2018.


  • Expert knowledge and experience of healthcare providers at Cleveland Clinic
  • Genetic and Rare Disease Information Center. Autoimmune Pulmonary Alveolar Proteinosis. Accessed 6/11/2018.
  • Borie R, Danel C, Debray MP, et al. Pulmonary alveolar proteinosis. Eur Respir Rev. 2011;20(120):98-107.
  • National Organization for Rare Disorders. Pulmonary Alveolar Proteinosis. Accessed 6/11/2018.
  • Alshati MH. Alveolar proteinosis: a slow drowning in mud. Cleve Clin J Med. 2014; 81(8):468-470. doi:10.3949/ccjm.81a.13085.
  • Kumar A, Abdelmalak B, Inoue Y, Culver DA. Pulmonary alveolar proteinosis in adults: pathophysiology and clinical approach. The Lancet Respiratory Medicine. January 2018. doi:10.1016/s2213-2600(18)30043-2.

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