Nail clubbing can have various causes, ranging in severity from 'very minor' to 'generally fatal'. Finding the true cause means ruling out or confirming each possibility – in other words, diagnosis.
Diagnosis is usually a complex process due to the sheer number of possible causes and related symptoms. In order to diagnose nail clubbing, we could:
Are your fingers or toes 'clubbed', being wider and bulging at the ends? Clubbed fingers or toes have nails that are wider and more rounded than normal, often curving downwards.
Possible responses:→ No, my fingers are normal width / don't know
→ Yes, slightly
→ Yes, there is very noticeable clubbing