The nail concave changes refer to the appearance of horizontal and vertical lines and spots on the nails. According to Chinese medicine, this change in the nail is closely related to the low function of the body’s tissues and organs, the destruction of tissue structures, atrophy and other pathological changes. So, what tests are needed for concave nails? The following are the examination methods for concave nails: 1. spots: a small amount of white spots on the nail is usually a sign of calcium deficiency, silicon deficiency or parasitic diseases; a larger number of white spots may be a sign of neurasthenia; and yellow fine spots on the nail may suffer from digestive system diseases; be careful if black spots appear on the nail, the lighter ones are just overworked and malnourished, the heavier ones may be signs of gastric prolapse, stomach cancer, and Uterus cancer precursors. 2, horizontal lines: the horizontal lines on the nail is a record of the lesions that have occurred. In other words, when there are horizontal lines on the nails, there must have been some lesions in the body. Generally speaking, at the beginning, the horizontal lines are only at the bottom of the nail, and as the nail grows, it gradually moves upwards, which indicates that it is getting closer to the onset of the disease. 3. Vertical lines: The surface of the nail is not smooth enough, and a straight line appears, which usually appears after overworking and overuse of the brain; these vertical lines will be clearly visible when there is a lack of sleep. If the vertical lines persist, it may be a chronic pathology of the internal organs. If not regulated, the nails will become uneven and even crack as the condition progresses.