Nail Clubbing Due to Smoking

Introduction:

Nail clubbing or finger clubbing is a variation in the normal shape and structure of the nail. The nail bed becomes soft and swollen, along with the roundness and downward curvature of the nail. The condition is prevalent amongst chronic (long-time) smokers. Clubbing of nails due to smoking occurs as a result of a lack of oxygen in the tissues, which occurs in lung and heart diseases induced by smoking. There are various stages of nail clubbing that can be analyzed by a simple test. Apart from diseases caused by smoking, there are several health conditions that can also lead to the clubbing of the nails. The frequency of nail clubbing in the population is unknown.

What Is Nail Clubbing?

Nail clubbing is defined as an abnormal change in the shape and structure of the nails, characterized by increased roundness of the nails, downward curving of the nails, enlargement of the fingertips, softening of the nail beds, bulging of the fingertips or toe tips, and increased angulation between the cuticles and the nails. Nail clubbing or finger clubbing in itself is not a disease, but mostly it is a symptom or warning sign of underlying health problems. Whereas, in some cases, nail clubbing can occur sporadically (occurring randomly with no apparent reason) or it can be congenital (a child is born with them). When nails or fingers get clubbed, the tissues under the nail bed become soft and swollen. The changes in the structure of the nails happen gradually over time and worsen depending upon the severity of the cause.

What Are the Stages of Nail Clubbing?

Nail clubbing usually occurs in five stages:

1. No Visible Signs of Clubbing: Softening of the nail beds only with no apparent changes in the nails.

2. Mild Clubbing: Loss of the normal angulation between the nail bed and the cuticle but nail clubbing is not visible at a glance.

3. Moderate Clubbing: Increased convexity of the nail fold, which means the angle between the nail bed and the cuticle increases further. Nail clubbing becomes more obvious at a glance.

4. Gross Clubbing: Thickening of the complete end part of the finger, and the finger will start resembling a drumstick.

5. Hypertrophic Osteoarthropathy: Appearance of striations (grooves, ridges, and layers) on the nails, and the nail appears shiny.

How Is Nail Clubbing Evaluated?

Nail clubbing is clinically evaluated with the help of studying the Schamroth’s sign or Schamroth’s window test. This is a simple test used to confirm nail clubbing with no laboratory testing methods involved. In this test, the corresponding fingers of the opposite hands are held against each other, with the bones of each finger near the nail bed touching each other. When a nail-to-nail contact is made, there should be an appearance of a diamond-shaped window near the nail beds and the nails of the two fingers. This window is known as the Schamroth’s window, and it will completely disappear in case of nail clubbing.

How Does Smoking Cause Nail Clubbing?

• The use of tobacco is harmful and hazardous to health. There are extremely dangerous substances in tobacco in many forms. This includes substances like nicotine, tar, acetone, carbon monoxide, etc.

• Smoking tobacco in the form of cigarettes or cigars is prevalent globally, even though the harmful effects of doing so are well known. Smoking causes not only temporary issues but also long-term serious health conditions.

• One of the very common signs in regular smokers is nail clubbing.

• Nail clubbing due to smoking occurs as a result of stimulation of the platelet-derived factor known as the vascular endothelial growth factor (VEGF). There is a lack of oxygen supply to the tissues (hypoxia) in the case of chronic smokers, which leads to stimulation of VEGF, and this VEGF, in turn, induces enlargement of the vessels, swelling, or edema, and growth of bone-forming and connective tissue-forming cells in the nails. In the case of chronic health conditions induced by regular smoking like lung cancer, bronchiectasis, cystic fibrosis, lung abscess, etc., this is the mechanism of action leading to nail clubbing.

• In the case of extra-pulmonary diseases caused due to smoking, like cyanotic heart disease, fragments of cells of the bone marrow responsible for the formation of platelets gain access to the systemic circulation and get trapped within the nail beds. These fragments then start releasing VEGF and other growth factors, leading to nail clubbing.

• Another way in which smoking causes nail clubbing is by increased production of prostaglandin E2 (PGE2), which is a fatty compound found naturally in the body to fight internal inflammation. This PGE2 is broken down by an enzyme produced by the lungs. Therefore, in the case of smoking-induced lung cancer, there is a reduction in the production of PGE2 breaking enzyme, which eventually leads to nail clubbing.

What Are the Health Conditions That Can Cause Nail Clubbing Due to Smoking?

The various health conditions that can cause nail clubbing due to smoking are:

• Lung Cancer: Tobacco smoking is the number one risk factor for lung cancer, and 80 % of the people with nail clubbing are associated with lung cancer. Nail clubbing is more common in non-small-cell lung cancer, with a prevalence rate of about 54 % of all cases. Whereas, in the case of small-cell lung cancer, the prevalence rate is less than 5 %. In case of nail clubbing due to smoking-induced lung cancer, the patient will have other symptoms like a persistent cough, difficulty in breathing, pain in the joints, weight loss, appetite loss, cough with blood, chest pain, etc.

• Interstitial Lung Disease: Nail clubbing is mostly seen in idiopathic pulmonary fibrosis, which is a condition characterized by thickening and stiffening of the lung tissues leading to scar tissue formation. This condition is common amongst regular smokers.

• Cystic Fibrosis: This is a lung disease that can be genetic or induced by regular smoking, characterized by increased mucus production leading to a build-up of mucus in the airways, intestines, etc.

• Bronchiectasis: This is a suppurative lung disease in which the tubes of the lungs get damaged.

• Heart Diseases: Any heart disease associated with hypoxia (low oxygen levels in tissues) will lead to the clubbing of nails.

What Are the Health Conditions That Causes Nail Clubbing?

There are other health conditions that may cause nail clubbing, but they are not associated with smoking. These health conditions include:

• Malabsorption of food can lead to a deficiency of several vital nutrients, which can lead to nail clubbing.

• Ulcerative colitis (formation of ulcers in the digestive tract).

• Liver cirrhosis (a chronic liver disease characterized by scarring or fibrosis of the liver tissues).

• Hepatopulmonary syndrome (an uncommon condition that affects the lungs along with the development of chronic liver diseases).

• Grave’s disease (overactive thyroid).

• Pseudoclubbing, in which the nails are bent out of shape in both the longitudinal and transverse axes (common amongst African descendants).

• Vascular abnormalities in one or both the arms.

What Tests Should Be Done in Case of Nail Clubbing Due to Smoking?

Since nail clubbing is, in fact, a symptom of other serious underlying health conditions, the healthcare provider may advise the following tests to be done:

• X-ray Chest or CT Scan (Computed Tomography): Imaging tests like an X-ray of the chest or a CT scan of the chest may be done to evaluate the chances of developing lung cancer, lung tumor, or any other lung disease.

• Pulmonary Function Test: This is a non-invasive test to evaluate the efficiency and ability of the lungs to function. The test measures lung volume, lung capacity, rates of flow, and gas exchange. The ability of the lungs to function properly is often hampered in the case of regular smokers because of the damage done to the lung tissues.

• Arterial Blood Gas: In this test, a sample of the blood is collected from the patient’s artery to measure the amount of oxygen and carbon dioxide in the blood. These levels are often imbalanced in case of lung and heart diseases.

• Electrocardiogram (ECG): It is a non-invasive and simple test to measure the heart’s rhythm and electric activities. Sensors attached to the skin during this test detect signals sent by the heart every time it beats.

• Echocardiogram: It is a type of ultrasound scan in which high-frequency sound waves create echos when they bounce off different parts of the heart and nearby vessels.

What Is the Management for Nail Clubbing Due to Smoking?

Clubbing of nails does not require any treatment, but the underlying cause leading to this clubbing will require treatment. The management of nail clubbing due to smoking is done in the following ways:

• Lifestyle changes are the first line of treatment for nail clubbing due to smoking. Breaking the habit of smoking and cessation of tobacco consumption should be the first step of treatment.

• If the underlying cause of nail clubbing is lung cancer, then chemotherapy, radiation therapy, and surgery may be done to cure cancer.

• A combination of oxygen therapy, lung rehabilitation, and medications is used to treat other lung disorders caused by smoking.

Conclusion:

Nail clubbing due to smoking is a common symptom seen in chronic smokers that is often an indication of a more severe underlying medical condition. No specific treatment for nail clubbing is available at the moment. However, nail clubbing can be reduced or reversed if the medical condition causing the clubbing is treated. But it can be reversed if the treatment is done early. Once tissue changes occur and there is enough collagen deposition, nail clubbing is unlikely to get reversed.