Thinning nails may be caused by non-disease factors or may be related to disease factors such as malnutrition, psoriasis and lichen planus. 1. Non-disease factors: such as congenital thinning of nails or frequent manicure excessive thinning caused by nail thinning. 2. Disease factors: (1) Nutritional deficiencies: lack of vitamins B and C as well as calcium, phosphorus, zinc and other elements can cause nail nutritional deficiencies and symptoms of thinning nails. (2) Psoriasis: when psoriasis affects the nails, it can cause nail lesions, which are mainly manifested as thinning of nails and unevenness of the nail surface in the form of pinholes. (3) Lichen planus: it is a chronic inflammatory disease, which can cause softening and thinning of nails and even longitudinal cracking when it involves nails. If there are symptoms of thinning nails, it is recommended to consult a doctor in time to find out the cause of thinning and then actively cooperate with the physician to carry out targeted treatment, so as to avoid delaying the condition.