Common causes of white nails include onychomycosis, anemia and psoriasis. 1. Ringworm of the nails: this disease is mainly caused by dermatophyte infection, the common causative organism is Trichophyton rubrum, which is manifested as smooth white dense spots with clear boundaries on the nails, and with the progress of the disease, the nails can gradually turn yellow, rupture easily, and unevenness and other symptoms. 2. Anemia: this disease is mainly due to blood loss, or unbalanced diet, disease factors, etc., resulting in the total volume of red blood cells in the systemic circulation of the blood is reduced to below the normal value, there may be symptoms such as white nails, thin and brittle nails, and rough skin. 3. Psoriasis: the etiology of this disease is unknown, can be related to genetics, infection, metabolic disorders and other factors, can be invaded to the nails, manifested as nail depression point small and shallow, nail plate lesions lose luster, whitening, thickening and other symptoms. Nail whitening can not be ruled out by other causes, it is recommended that patients consult a regular hospital in a timely manner, after a clear diagnosis, under the guidance of the doctor timely treatment.