Ridges across fingernails can have various causes, just like most other symptoms. 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 ridges across fingernails, we could:
Do your fingernails have ridges or grooves going from side to side, across the direction of growth?
Possible responses:→ No / don't know
→ A few / minor
→ Many / pronounced
Nail abnormalities are a possible symptom of psoriasis.