Clubbed Fingers as an Early Sign of Illness

4. Diagnosis

Because clubbing sometimes starts subtly, people may not notice for months, which may delay necessary treatment. Once an appointment is made, a doctor will attempt to determine whether the patient meets the diagnostic criteria. There are a few signs the doctor may check for, including loss of the natural nail angle. Doctors sometimes use the Schamroth window test to diagnose clubbing. If you hold the backs of the left and right fingers against each other, you should see a small diamond-shaped hole where light shines through. In fingers that have clubbing, this hole is missing.