From the Guidelines
Bilateral clubbing is primarily caused by chronic hypoxemia, which leads to vasodilation and increased blood flow to the extremities, with the most common causes including cardiopulmonary conditions such as cyanotic congenital heart disease, interstitial lung disease, and chronic obstructive pulmonary disease, as noted in the most recent study 1.
Causes of Bilateral Clubbing
The causes of bilateral clubbing can be categorized into cardiopulmonary and non-pulmonary conditions.
- Cardiopulmonary conditions:
- Cyanotic congenital heart disease
- Bronchiectasis
- Lung cancer
- Interstitial lung disease
- Chronic obstructive pulmonary disease
- Non-pulmonary causes:
- Inflammatory bowel disease (particularly Crohn's disease and ulcerative colitis)
- Liver cirrhosis
- Endocarditis
- Genetic factors, such as pachydermoperiostosis or primary hypertrophic osteoarthropathy
- Certain infections like tuberculosis, lung abscess, and empyema
Pathophysiology
The pathophysiology of bilateral clubbing involves tissue hypoxia triggering the release of growth factors and platelet-derived growth factor, which promote vascular proliferation and connective tissue changes in the nail beds, resulting in the characteristic bulbous fingertips, increased nail bed angle (greater than 160 degrees), and sponginess of the nail base, as described in 1.
Clinical Presentation
The clinical presentation of bilateral clubbing may include digital clubbing, failure to thrive, or respiratory failure, as well as hypoxemia and diffuse abnormalities on a chest radiograph or computed tomography scan, as noted in 1.
Management
Identifying the underlying cause of bilateral clubbing is essential for proper management, which may involve treatment of the underlying condition, as well as monitoring for complications such as lung disease, as recommended in 1.
From the Research
Causes of Bilateral Clubbing
Bilateral clubbing, also known as digital clubbing, is a condition characterized by the enlargement of the tips of the fingers or toes. The causes of bilateral clubbing can be attributed to various underlying medical conditions. Some of the possible causes include:
- Pulmonary diseases, such as cystic fibrosis 2, idiopathic pulmonary fibrosis 3, 4, and lung cancer 5
- Interstitial lung disease (ILD) 4, 6
- Pulmonary hypertrophic osteoarthropathy 5
Association with Pulmonary Conditions
Bilateral clubbing has been found to be associated with poor prognosis and is variably present in patients with idiopathic pulmonary fibrosis (IPF) 4. The presence of clubbing in patients with ILD has been linked to lower pulmonary function and higher serum KL-6 levels 6. Additionally, clubbing has been observed in patients with lung cancer, particularly those with squamous cell carcinoma 5.
Assessment and Prevalence
The assessment of clubbing can be done using various methods, including the phalangeal depth ratio, digital index, and Schamroth sign test 4. However, these methods have been found to have poor correlation, resulting in varying prevalence rates of clubbing in patients with fibrotic ILDs 4. The prevalence of clubbing in patients with ILD has been reported to range from 7 to 42% 4, and 16.7% in another study 6.