Ribbed vertical lines on nails may be caused by nail fungus disease, hypothyroidism, vitamin A deficiency, etc. It is recommended to consult a doctor in time to clarify the cause of the disease. 1. Nail fungal disease: mainly caused by fungi invading the nail plate and subnail tissues, showing that the surface of the nail is uneven or loses its luster, and prismatic vertical lines may appear. 2. Hypothyroidism: It is mainly caused by reduced synthesis or secretion of thyroid hormone or insufficient physiological effect of thyroid hormone, which leads to lower metabolism of the body, and it can show symptoms such as unevenness of nails and cracks on the surface. 3. Vitamin A deficiency: the surface of healthy nails is smooth, if there are obvious ribbed vertical lines, may be caused by vitamin A deficiency. Lack of vitamin A can cause dry skin, flaking, dry hair easy to fall off, finger (toe) nails become brittle and easy to fold, more lines and other manifestations. It is recommended to go to the hospital in a timely manner, after clarifying the cause of the disease under the guidance of the doctor to carry out targeted treatment.