Flat and wide nails may be related to genetic factors, or may be caused by pathological factors such as damage to the nail bed, calcium deficiency, nail fungus disease, iron deficiency anemia, etc. 1. Genetic factors: If family members such as parents, grandparents and grandmothers also have symptoms of flat and wide nails, then it is considered to be a familial disease, which is caused by hereditary factors, and usually can not be changed and does not need to be treated. 2. Pathological factors (1) Damage to nail bed: If the nail is squeezed or frequently bitten, the nail bed may be damaged, and the curvature and shape of the nail may be changed, resulting in the symptoms of flat and wide nails. (2) Calcium deficiency: Calcium deficiency may affect the development of the nails, which may result in the nails becoming wide and flat, thin and soft. (3) Nail fungus disease: Fungal infections that invade the nail plate may cause symptoms such as flat and wide nails, discoloration, separation, and even loss of nails. (4) Iron deficiency anemia: In addition to anemia symptoms such as weakness, palpitations, pallor, dizziness, fatigue, etc., symptoms such as flat and wide nails and lack of luster may also occur. There are other reasons for the symptoms of flat and wide nails (e.g. lack of trace elements affecting the function of the nail matrix), it is recommended to go to the hospital to identify the causes and then actively treat them, so as not to delay the condition.