What is finger clubbing?

Finger clubbing is also called digital clubbing or Hippocratic fingers.In medicine, clubbing (also known as "Drumstick fingers," "Hippocratic fingers," and "Watch-glass nails"[1]) is a deformity of the fingers and fingernails that is associated with a number of diseases, mostly of the heart and lungs.Idiopathic clubbing can also occur. Hippocrates was probably the first to document clubbing as a sign of disease, and the phenomenon is therefore occasionally called Hippocratic fingers. It is the phrase doctors use to describe specific changes in the shape of the fingers and fingernails. People with heart or lung problems sometimes have these changes. They usually develop in advanced disease.
Signs and symptoms

Clubbing develops in five steps:[3]

1. Fluctuation and softening of the nail bed (increased ballotability)
2. Loss of the normal <165° angle (Lovibond angle) between the nailbed and the fold (cuticula)
3. Increased convexity of the nail fold
4. Thickening of the whole distal (end part of the) finger (resembling a drumstick)
5. Shiny aspect and striation of the nail and skin

Schamroth's test or Schamroth's window test (originally demonstrated by South African cardiologist Dr Leo Schamroth on himself[4]) is a popular test for clubbing. When the distal phalanges (bones nearest the fingertips) of corresponding fingers of opposite hands are directly apposed (place fingernails of same finger on opposite hands against each other, nail to nail), a small diamond-shaped "window" is normally apparent between the nailbeds. If this window is obliterated, the test is positive and clubbing is present

Finger clubbing happens in more than 3 out of 10 people (35%) with non small cell lung cancer but only about 4 out of 100 people (4%) with small cell lung cancer. You may also get it with mesothelioma.

If you have finger clubbing, your doctor should send you for a chest X-ray to check your heart and lungs.

Finger clubbing occurs in stages. First the base of the nail (nail bed) becomes soft and the skin next to the nail bed becomes shiny. The nails then curve more than normal when looked at from the side and this is called Scarmouth's sign. The ends of the fingers may then get larger and are called 'drumstick fingers'.

Clubbing is thought to be caused by fluid collecting in the soft tissues at the ends of the fingers. This is caused by more blood flowing to the area than usual, but we don’t fully understand why this happens. It may be due to the tumour producing particular chemicals or hormones, which is called a paraneoplastic syndrome.

In the later stages, extra areas of bone may form on the finger joints, wrists and ankles. This is sometimes mistaken for arthritis and is called hypertrophic pulmonary osteoarthropathy.

Finger clubbing is unusual. If you have it and are concerned, do go and speak to your doctor.