Clubbing may result from chronic low blood-oxygen levels. This can be seen with cystic fibrosis, congenital cyanotic heart disease, and several other diseases. The tips of the fingers enlarge and the nails become extremely curved from front to back.
Review Date 5/17/2019
Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.