Vertical lines appear on the thumb nail, which should be considered to be caused by a variety of conditions. First, the nail longitudinal ridge: this is a normal physiological phenomenon, may also be a clinical manifestation of nail dystrophy, usually do not need to deal with. Nail dystrophy: it is divided into congenital nail dystrophy and acquired nail dystrophy. 1, congenital nail dystrophy: it is related to autosomal dominant inheritance, including ectodermal dysplasia, maculopapular epidermolysis bullosa, etc. 2, acquired nail dystrophy: it is related to nutrient deficiencies, including vitamin deficiencies, iron-deficiency anemia, pulmonary dysfunction, hypothyroidism and so on, and it is generally recommended to treat the original disease. 3, gray nail: it is a normal physiological phenomenon, and may also be a clinical manifestation of nail dystrophy. 3, gray nails: gray nails is also clinically referred to as nail fungal disease, the main common fungi including red fungus, ringworm fungus, etc., you can choose to take oral antifungal drug treatment.