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Pulmonology Cardiopulmonary Examination Intermediate
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Clubbing Causes: CLUBBING

C
L
U
B
B
I
N
G
High-yield differential diagnosis for digital clubbing (loss of Lovibond angle > 165 degrees).

Digital clubbing results from megakaryocytes escaping pulmonary capillary fragmentation in unoxygenated or shunted blood; they lodge in distal digits and release PDGF and VEGF, stimulating periosteal proliferation.

Systematic Breakdown

C

Cyanotic Congenital Heart Disease / Cystic Fibrosis

Right-to-left shunts (Tetralogy of Fallot) and chronic suppurative CF bronchiectasis.

L

Lung Cancer (Bronchogenic Carcinoma)

Non-small cell lung cancer (especially adenocarcinoma); part of hypertrophic pulmonary osteoarthropathy (HPOA).

U

Ulcerative Colitis & Crohn's Disease

Inflammatory bowel disease with chronic systemic inflammation.

B

Bronchiectasis

Permanent airway dilation from chronic necrotizing infections.

B

Benign / Familial

Idiopathic hereditary clubbing without systemic pathology.

I

Infective Endocarditis / Idiopathic Pulmonary Fibrosis

Subacute bacterial endocarditis and restrictive fibrotic lung disease.

N

Neoplasm (Pleural Mesothelioma, Hodgkin)

Thoracic malignancies stimulating localized vascular growth factors.

G

GI Cirrhosis

Biliary cirrhosis and hepatopulmonary syndrome.

High-Yield Clinical Pearls & Exam Tips
  • Schamroth's Window Test: Obliteration of the diamond-shaped window created when dorsal surfaces of terminal phalanges of corresponding fingers are apposed.
  • Crucial Rule: COPD alone does NOT cause digital clubbing! If a COPD patient exhibits clubbing, suspect underlying bronchogenic carcinoma.
Related Pharmaceuticals
Oxygen Therapy
Related Clinical Conditions
Bronchogenic Carcinoma Cystic Fibrosis Tetralogy of Fallot Idiopathic Pulmonary Fibrosis
Authoritative Sources: Macleod's Clinical Examination 14e · First Aid USMLE Step 1

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