Clubbing

Clubbing refers to a painless enlargement of the ends of fingers or toes, giving them a bulbous or drumstick appearance with increased nail curvature. It is often a sign of chronic disease, especially of the lungs, heart, or gastrointestinal system.

🔍 Definition

Clubbing is the broadening and thickening of the fingers or toes due to proliferation of connective tissue beneath the nail bed.

🧠 Mechanism / Pathophysiology

Exact cause unknown.

Believed to involve:

Increased blood flow to distal phalanges

Vascular endothelial growth factor (VEGF) release due to chronic hypoxia

Platelet-derived growth factor (PDGF) and megakaryocyte fragments stimulating tissue growth

👀 Clinical Features / Stages (Lovibond’s Stages)

Fluctuation of nail bed – nail bed becomes spongy

Loss of Lovibond’s angle – normal angle between nail and nail bed (<160°) increases (>180°)

Increased curvature of nail (both longitudinal and transverse)

Drumstick appearance – bulbous enlargement of fingertip

Hypertrophic osteoarthropathy (advanced) – periostitis of long bones with joint pain and swelling

🧪 Differentiation
Feature Normal Clubbed
Lovibond angle <160° >180°
Nail bed feel Firm Spongy
Profile sign Visible gap No gap
⚕️ Causes of Clubbing
🫁 Pulmonary causes (most common)

Bronchogenic carcinoma (lung cancer) – most common cause in adults

Bronchiectasis

Lung abscess

Empyema

Cystic fibrosis

Interstitial lung disease

❤️ Cardiac causes

Cyanotic congenital heart disease

Infective endocarditis

Atrial myxoma

🍽️ Gastrointestinal / Hepatic causes

Cirrhosis (especially biliary cirrhosis)

Inflammatory bowel disease (Ulcerative colitis, Crohn’s disease)

Malabsorption syndromes

Liver abscess

🦴 Miscellaneous

Familial (hereditary)

Thyroid acropachy (in Graves’ disease)

Idiopathic

⚠️ Important Associations

Unilateral clubbing → Aneurysm or malignancy of one side of the thorax

Clubbing + joint pain → Hypertrophic osteoarthropathy

Rapid onset clubbing → Often malignancy (e.g., lung cancer)

🧩 Mnemonic for Causes of Clubbing — “CLUBBING”

C – Cyanotic heart disease
L – Lung cancer, Lung abscess
U – Ulcerative colitis
B – Bronchiectasis
B – Bronchial carcinoma
I – Idiopathic / Interstitial lung disease
N – Neoplasm (thoracic)
G – GI diseases (Cirrhosis, Crohn’s, etc.)