A thin white arc on the front of the nail can be caused by vitamin or trace element deficiency, trauma, nail fungus and other factors. 1. Lack of vitamins or trace elements: when the lack of calcium, iron, zinc and other trace elements, or vitamins, may appear in front of the nails have a thin circle of white arc, usually accompanied by poor nail gloss, thin nails, easy to break and other symptoms. 2. Trauma: If the nail area is hit, extrusion and other trauma, it may lead to white arcs on the edge of the nail. 3. Ringworm of the nails: when the skin fungus infects the nails and causes ringworm of the nails, a white arc may appear on the edge of the nails, and there are also symptoms such as discoloration and unevenness of the nails. 4. Other diseases: Anemia, abnormal thyroid function, rheumatoid and other diseases may also lead to abnormal nail manifestations. It is recommended that patients with a thin white arc on the front of the nail should consult a doctor in order to clarify the cause of the disease and treat the symptoms.