• Pathophysiology
  • Clubbing is observed in cardiopulmonary disease states where hypoxic-inflammatory pathways are activated, releasing platelet and fibroblast-derived growth factors (especially VEGF) that promote platelet clumping/embedment in the distal capillary beds (fingers, toes), which then leads to local fibrovascular proliferation.
• Associated conditions
  • Respiratory conditions, such as:
    • Interstitial lung disease
    • Idiopathic pulmonary fibrosis
    • Cystic fibrosis
    • Lung cancer
  • Cardiovascular conditions, such as:
    • Cyanotic congenital heart disease
    • Cardiac shunts
  • Infections, such as:
    • Tuberculosis
    • Infections causing lung abscesses
  • Hypertrophic osteoarthropathy: a syndrome (either hereditary or paraneoplastic) that manifests with painful nail clubbing, synovial effusions, and periostitis
  • IBD
  • Not associated with COPD, asthma
    • COPD per se does not cause clubbing, but if clubbing is present in COPD, underlying lung cancer and bronchiectasis must be ruled out.