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 covers the causes and symptoms of clubbed fingers and clubbed nails, along with how clubbed fingers are diagnosed and treated.

Primary vs Secondary Clubbing

Clubbed fingers, nails, or toes are typically a sign of severe disease, but not always.

Primary (idiopathic) clubbing is clubbing that occurs alone, without the presence of any underlying disease. Primary clubbed fingers, toes, and nails are a rare inherited trait—accounting for just 3% of all clubbing cases.

Secondary clubbing occurs as an effect of another health problem, such as lung cancer, heart disease, or cirrhosis of the liver. In fact, secondary clubbing is caused by lung cancer or lymphoma in approximately 80% of cases.

Symptoms

Clubbing can involve your fingers and/or toes. It is typically bilateral (affecting both hands and/or feet) and it should be equal in terms of its extent on both sides.

Clubbed nails become red, sponge-like, and swollen, almost like tiny balloons. 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.

If you or your child has primary HOA, then your fingers or toes may naturally appear large, bulging, and rounded. This will be noticeable during childhood or during the teenage years, and it will not change much over time. With primary HOA, other family members are also likely to have finger clubbing and/or toe clubbing.

Secondary clubbing happens gradually, and it causes a change in the appearance of your fingers and/or toes. With secondary clubbing, which is caused by disease, you would also have other features that are not seen in primary clubbing.

Features of secondary clubbing include:

• Softening of the nails
• Nail beds that soften and feel spongy
• Nails that seem to "float" instead of being firmly attached to your fingers
• Disappearing of the angle between your nails and cuticle
• Enlargement or bulging of the distal portion of your finger (where your finger meets your nail)
• Warm, red nail beds
• Nails that curve downward and look like the bottom of the round part of a spoon

Eventually, the nail and skin around the nail may become shiny, and the nail develops ridging. 

Causes

Primary clubbing is hereditary, and it is passed down via genes. Hereditary clubbing is simply a physical feature, like the color of your eyes or your height. Several genes have been associated with primary clubbing, including the HPGD gene and the SLCO2A1 gene.

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 secondary 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.

How Clubbing Affects Nail Beds

The medical conditions that can cause clubbing are generally associated with decreased oxygen levels. Experts suggest that clubbing occurs as your body undergoes changes in response to low oxygen.

Several processes affect the nail beds in secondary clubbing. The nail enlargement occurs due to the growth of excess soft tissue beneath the nail beds. The enlargement is associated with inflammation and a proliferation of small blood vessels in the nail beds.

Diagnosis

Clubbing can be subtle, so it may be difficult for you and your medical team to verify this change in your digits.

There are a few objective criteria that are used to assess clubbing, and they can help in determining whether you have developed this physical change:

• Lovibond's profile sign: Normally, there is a sharp angle between the nail bed and the cuticle. When you have clubbing, the natural angle is lost as the nail angles down instead of up.
• Distal/interphalangeal depth ratio: The phalanges of your finger are the sections between each bending joint. Your distal phalange, the one that includes your nail, is normally shorter depth-wise than the neighboring phalange. Clubbing is indicated when the opposite is true.
• Schamroth's sign: The sharp angle between your nail bed and cuticle forms a tiny diamond-shaped hole when you place your hands together with the top of your nails facing each other. When this gap disappears, it is described as Schamroth's sign.

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.

Treatment

Usually, the abnormal shape and size of the digits do not cause health problems, but any underlying disease that causes clubbing needs to be medically and/or surgically managed, as appropriate. Treatments may prevent your clubbing from worsening and, in rare cases, can reverse some or all of the physical features of clubbing.

There are a variety of approaches used to treat the underlying cause of clubbing. Your treatment will depend on your situation. You may need management of respiratory disease, treatment of heart disease, or interventional therapy for cancer.

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.

A Word From Verywell

If you notice clubbed fingers or toes, be sure to discuss this with your healthcare provider. Clubbing can be diagnosed in your healthcare provider's office. Although clubbing itself is harmless and doesn't require treatment, it is often associated with health conditions that can worsen without treatment.