Nail clubbing

Brief overview of nail clubbing

When you see a patient with shoulder pain, what triggers you to look at a patient’s hands? Is it a patient with bilateral shoulder pain? or perhaps if the patient has a history of smoking?

Looking at a patients hands may seem strange at first, but it could play an important role in your assessment and decision making. Take for example someone with right shoulder pain. After further questioning, they then go onto tell you about their other joint pains. Now, when looking at their hands, they have bilateral swelling in their hands. This starts to build up a bigger picture of what could be going on (See NICE guidelines re: Rheumatoid Arthritis) and where you may go next with this patient.

Nail clubbing

This then brings us onto nail clubbing. This is a sign which is characterised by soft tissue swelling of the terminal phalanx and a change between the nail bed and nail. To get a good understanding of the pathophysiology of which this sign presents like this, then this video gives you an excellent overview (this is way to complicated for me and this blog!).

Hand showing nail clubbing

This sign seems to be important because although it is not common (1% of general medicine admissions), it is associated with more sinister diseases (40%) in those that have it. These diseases include the following:

Table taken from Sarkar et al., (2012)

If you are in the UK, you may also be aware that this sign is part of the NICE guidelines for suspecting lung (including pancoast tumour) and mesothelioma cancer.

Taken from the NICE guidelines for suspecting cancer

Assessment of nail clubbing

So I am sure we can agree that it is a sign we should be looking out for. We can use the following measurements and signs to help guide our suspicions.

- Schamroth sign

This is when the gap is gone between your digits when placed together

- Lovibond angle

This is when the proximal nail fold and nail is >180°

- Phalangeal depth ratio

This is when the depth of the digit is greater distally at the nail than the distal joint line of the phalanx

- Hyponychial angle

This is an angle calculation using three points on the distal digit which should usually be <180°

As always, if anyone has any comments, further reading or suggestions on this topic please feel free to fire them at me on here or on my Twitter/X. I am always learning and any discussions would be thoroughly welcomed!