Thumb nail depression, generally related to the following factors: First, hypoxemia. Hypoxia can cause the body arterial oxygen partial pressure drop, resulting in peripheral tissue blood circulation hypoxia, causing nutritional metabolic disorders of the nails, the formation of nail depression. Second, heavy physical labor. In the crowd of nail depression, heavy manual labor is more than light manual labor, the intensity of labor has a certain effect on nail depression. Nutritional status. Iron-deficiency anemia and Raynaud’s disease, which causes ischemia of the fingertips, can cause nails to be sunken, indicating that nails have a certain relationship with nutrition. Prolonged exposure to cold water, frequent use of cold water to wash hands or frequent exposure to chemical substances can also lead to thumb nail depression. On weekdays, it is necessary to strengthen physical exercise, increase the body’s immunity, do a combination of work and rest, relax and reduce stress. Pay more attention to supplementing vitamins and minerals in your diet, for example, eat more fresh vegetables and fruits, and pay attention to make sure to eat breakfast and eat a reasonable diet, and if you have the conditions, you can go to supplement vitamins and minerals.