Diagnostics

• Perform a thorough clinical evaluation.

  • Past medical history and family history for pulmonary and/or autoimmune conditions

  • Physical examination, including evaluation for signs of connective tissue disorders

• Obtain HRCT of the chest to evaluate for IPF and other alternative diagnoses.

• Obtain laboratory studies to screen for CTD-ILD.

• Perform pulmonary function tests to assess disease severity and treatment response.

• If diagnosis remains unclear, consider:

  • Additional laboratory studies based on clinical suspicion

  • Invasive testing

Usual interstitial pneumonia (UIP) pattern is highly specific for IPF.

• Typical UIP pattern findings

  • Honeycombing: multiple cystic lesions within the lung parenchyma due to fibrosis

  • Irregular thickening of intralobular septa

  • Reticular pattern and mild ground glass opacity (GGO)

  • Traction bronchiectasis (irreversible dilatation of the bronchi and bronchioles due to fibrosis) or bronchiolectasis

  • Pulmonary ossification may be seen.

• Interpretation

  • If UIP pattern is present, a definitive diagnosis can be made without histopathologic confirmation.

  • If other patterns are present, further evaluation is required to determine the cause.

• Restrictive lung disease pattern

  • ↓ Total lung capacity and ↓ vital capacity

  • Normal or ↓ FEV1

  • ↓ FVC

  • Normal or ↑ FEV1:FVC ratio

• Decreased diffusing capacity for CO (DLCO): highly sensitive parameter

X-ray chest

• Normal in approx. 10% of patients

• Predominantly basilar increase in reticular opacities (sign of fibrosis)

• Patients may have nodular or mixed patterns.

Additional laboratory studies

• CBC with differential

  • Anemia

  • Eosinophilia

• Liver enzymes: ↑ GGT, ↑ ALT, and/or ↑ AST

• BMP: ↑ creatinine

• Urinalysis: RBC casts, and/or dysmorphic RBCs

• ABG: nonspecific findings in patients with ILD

  • ↑ Alveolar-arterial oxygen gradient

  • ↓ PaO2

• Serum biomarkers for IPF: not recommended

Invasive testing

Obtain invasive testing if the diagnosis remains unclear and results will affect management.

• Bronchoscopy with bronchoalveolar lavage (BAL): Cellular analysis may help identify an underlying cause of ILD and exclude IPF.

• Surgical lung biopsy

  • Obtain if the diagnosis remains unclear after BAL.