Nail clubbing is a very old type of nail issue that has been reported since ancient times. It designates a deformity of the nails, which grow at a different angle from the nail base. It has been described for the first time between 460 and 370 BC by Hippocrates of Kos, a classical Greek doctor known as the Father of Medicine. This is why the condition is also named "Hippocratic fingers", as well as "digital clubbing" or "clubbing of fingers".
This condition makes fingertips become larger than normal, with a rounded shape, because both the base and top of the nail are deformed. Sometimes the nail can be curved at a very unusual angle of 180 degrees or more. This can also cause the nail beds to get softer while the fingertips grow in size. In most cases, the nail bed angle is around 160 degrees and the nail has a rounded shape. However, the nail itself is usually healthy, with a smooth surface. Nail clubbing can be a sign of a very serious heart disease, often of a congenital nature.
Scientists don't understand well the entire chain that causes nail clubbing but clinical evidence links it to a lower level of blood oxygen, due to either a blood disease or a lungs one. It is also known to be the effect of some other issues, for example digestive disorders or malignancies. The condition progresses slowly in time and most people only become aware of it long after it has become established. It can sometimes cause some minor fingertip discomfort but it is rarely painful. Some complications are known but are very rare, examples include pachydermoperiostosis and palmoplantar keratoderma.
Nail clubbing starts and evolves slowly in most patients but might progress very fast in rare situations. If the condition is a side effect of another disease, it might disappear after the main problem is treated and cured.
While the exact mechanism of nail clubbing is poorly understood, it seems to be caused by changes in the bloodstream as a result of several diseases. If specific compounds in the blood stream become active, they can have a direct effect on the nail bed. Clubbing is actually triggered by the thickening of the tissues under the nail plate, which forces the nail to grow wider. This effect can actually have multiple causes, since many diseases can lead to it.
The main cause of nail clubbing is usually lung disease. The most severe of these is lung cancer, a lethal problem that happens when cells in the lungs start to grow uncontrolled and form tumours. Another possible cause is cystic fibrosis. This causes secretions to build up in the lungs but is not actually a lung-specific disease but actually a systemic issue that prevents the normal circulation of water and salt through the body. Inhaling fibers of the toxic chemical asbestos can hurt and scar tissues inside the lungs, a condition known as asbestosis. The tissues can also become scarred and grow thicker due to pulmonary fibrosis, a poorly understood disease with causes that are often unknown. Another possible lung issue that can cause nail clubbing is bronchiectasis. In this case, lungs become unable to eliminate mucus due to infections or other problems that make airways become scarred and wider than normal.
Besides lung diseases, there are a number of other disorders that can trigger nail clubbing. These include tetralogy of fallot (TOF) and other congenital heart problems, liver diseases, Crohn's disease or related conditions that make the intestines inflamed, as well as Hodgkin's lymphoma and other varieties of cancer. Graves' disease and a number of similar conditions can make the thyroid gland too active, which is another possible cause of nail clubbing.
Nails on both fingers and toes can be affected by nail clubbing. The physical change of the nails is caused by another disease, which can be a serious one.
The deformities that are collectively known as clubbing start with an increased angle between the cuticle and the nail. This makes nails grow wider and with a rounder shape, which also gives them a downward curve. The increased size of the nail also makes the fingertips larger, sometimes causing minor irritation or redness. Another side effect is that nail beds become softer than normal.
Since nail clubbing has many possible causes, the speed of these changes is highly variable. They can happen very fast, in a matter of weeks, or progress slowly over a few years. If you notice clubbing on your nails, you should go see a doctor because this condition can signal other very serious diseases.
In most cases, nail clubbing develops over several years. Some conditions can cause the changes to happen very fast, examples include thorax empyema or lung infections.
Nails start to grow at an increases angle from the cuticles, larger than the maximum normal one of 165 degrees (known as the Lovibond angle). This makes the nail fold become more and more convex in shape, while the finger tips gets larger until it starts to look like a drumstick. Another change is the so-called increased ballot ability, or the nail bed becoming softer. The nails and the skin surrounding them can also start to have striations and a shiny or glossy appearance.
Nail clubbing can't be treated directly, not even surgery can correct it. If the root disease is treated and cured, the conditions might disappear but this is not always the case. Heart valve defects are one type of problem that can be corrected through surgery, which also restores the normal aspect of nails.