Nail Clubbing of the Fingers or Toes

Nail clubbing describes fingernails or toenails that are curved downward (like a spoon). The nails may feel soft when pressed and no longer sit even with the cuticle. This often occurs along with swelling or bulging of the tips of the fingers or toes as well.

Clubbed nails are not always cause for alarm, especially if nail clubbing runs in your family. Sometimes, though, nail clubbing is a warning sign of a serious condition such as a lung or heart condition or certain cancers.

This article explains the symptoms and causes of nail clubbing. It also details how healthcare providers use tests to make a diagnosis.

Nail Clubbing Stages and Symptoms

Physical changes in the fingernails are the surest sign of nail clubbing. Clubbing can also occur on the toenails. Clubbed nails become red, sponge-like, and swollen, almost like tiny balloons. This growth appears to occur from side to side as well as lengthwise.

Most often, clubbing occurs gradually. But the changes can occur rapidly, too, over a period of weeks. Either way, there are usually stages of progression.

• In the first stage, the nail bed softens. This isn't usually something you can see.
• In the second stage, the angle between the tissue above the visible top of your nail and the nail itself begins to change.
• In the third stage, the clubbing becomes easier to see as the nail starts to adopt a convex shape.
• In the late stages, the tip of the finger itself becomes thicker and wider. The nail and skin may take on a shiny appearance.

From close-up or a distance, clubbed nails resemble upside-down spoons. These changes may occur alone or with other symptoms, such as shortness of breath or coughing.

What Causes Clubbed Nails?

Nail clubbing occurs from a buildup of tissue in the ends of the fingers (terminal phalanges). The nails become enlarged and curve downward. Why this happens is still largely a mystery to researchers.

It's thought that dilated blood vessels cause the fingers to swell, leading to the appearance of clubbing.

What is known is that the causes of clubbing fall into three categories:

Idiopathic: This is a category in which clubbing occurs for no obvious reason. It is unrelated to a medical issue; it just happens.

Inherited trait: There are a few ways that clubbing can be inherited. Most often the trait is inherited in an autosomal dominant fashion, meaning that if one of your parents carries the trait, there is a 50-50 chance that you will, too.

Secondary clubbing: This refers to clubbing that occurs as a result of a medical condition. Most often, secondary clubbing is related to a condition of the heart or lungs, such as:

• Lung cancer: This cancer accounts for about 90% of all clubbing cases, with nearly 30% of lung cancer patients experiencing clubbing. The deformity is more common among people with non-small cell lung cancer than small cell lung cancer.
• Interstitial lung disease: A condition characterized by inflammation and scarring of the tissue around the alveoli, which are tiny air sacs in the lungs.
  
• Other lung conditions: Some lung conditions linked to clubbing include bronchiectasis, idiopathic pulmonary fibrosis, empyema, pulmonary tuberculosis, and cystic fibrosis.
• Congenital heart disease: Heart disease that is present from birth, especially cyanotic heart disease (a defect), often leads to clubbing.
• Infectious endocarditis: This infection in the lining of the heart chambers and valves can be caused by bacteria or some other infectious organism.

Sometimes nail clubbing can have causes that are unrelated to the heart or lungs, such as:

• Endocrine problems: Hyperthyroidism, especially Graves' disease, may be accompanied by clubbing.
• Gastrointestinal conditions: People with celiac disease (a chronic disorder of the digestive tract), cirrhosis, Crohn's disease, and ulcerative colitis may develop clubbing.
• Other cancers: Hodgkin's lymphoma often triggers clubbing.

When to See a Healthcare Provider

If you notice signs of nail clubbing, make an appointment to see your healthcare provider. Because clubbed nails can be a sign of a serious condition, it is important to have them evaluated right away.

Diagnosis

Clubbing is often easy to diagnose based on a visual exam alone. But a healthcare provider may do other measurements to confirm the diagnosis:

• Distal/interphalangeal depth ratio, which basically measures a finger's depth between the skin and nail bed
• Lovibond angle, which focuses on the angle between the base of the nail and the nail
• Schamroth sign, which is the lack of a "window" (gap) between the fingers when the digits from each hand are placed together and the tops of both hands are touching

A healthcare provider with experience in nail clubbing can be an invaluable resource.

Tests

If your healthcare provider decides you have clubbing, their first move will be to ask about your family history. They'll be interested to know if it's a hereditary trait.

The provider will then do a careful history and physical exam, keeping in mind the possible causes associated with secondary clubbing. Depending on your symptoms, the tests may include:

• A chest X-ray and possibly a CT scan to look for lung cancer as well as other lung and heart-related conditions
• An electrocardiogram (EKG) and/or echocardiogram to evaluate your heart
• Arterial blood gases and/or pulmonary function tests to evaluate your lung function and look for underlying lung diseases
• Blood tests, such as liver function tests and thyroid function tests

The next move, if any, will depend on what your healthcare provider discovers.

Chronic kidney disease and other disorders such as systemic sclerosis may cause finger changes that mimic the appearance of digital clubbing. Additional tests may be needed to rule these out.

Nail Clubbing Treatment

There is no specific treatment plan for clubbing itself. The key is to find the underlying cause of the clubbing and treat that.

When the underlying cause has been successfully treated, the clubbing should go away on its own.

This may involve management by a specialist, depending on the cause. These could include pulmonologists, oncologists, infectious disease specialists, cardiologists, gastroenterologists, endocrinologists, and/or radiologists.

Summary

Nail clubbing causes the fingers (or toes) to swell and turn red while the nails turn downward. It could be just an inherited family trait or it could be a sign of a serious medical condition involving the heart, liver, lungs, intestine, or stomach. In fact, 90% of all clubbing cases are caused by lung cancer.

Pinpointing the cause of clubbing is important. Once the cause is treated, the clubbing should go away on its own.