Sunken thumb nails do not represent liver damage, there are many causes of sunken nails, such as anemia, trauma, onychomycosis, etc. Liver damage usually does not directly lead to sunken thumb nails. 1. Common causes of sunken thumb nails: (1) Anemia: for example, iron deficiency anemia may cause spoon-shaped nails, which may lead to sunken thumbnails. (2) Trauma: Nails that have been crushed or bruised by external forces or that are often over-exerted may also cause a sunken thumbnail. (3) Onychomycosis: Onychomycosis caused by a fungal infection may also lead to a sunken thumbnail. There may be other causes of thumbnail depression that require further examination. (2) Liver injury: There are many clinical causes of liver injury, such as various types of hepatitis, as well as alcoholic liver, fatty liver, and drug-related liver injury. It may cause symptoms such as discomfort in the liver area, dry mouth, bitter taste in the mouth, fatigue, loss of appetite and jaundice in the skin. If there is any abnormality in your body, you should go to the hospital in time to clarify your condition and take treatment measures under the guidance of your doctor.