The sudden appearance of gray hair to black in the elderly, if only part of the hair becomes black can not be too worried, it may be physiological. For example, the quality of life of the elderly has been improved, the previous poor nutrition led to the growth of gray hair, now nutrition improvement, regular work and rest, happy mood and other factors may make it dark again. However, some patients with mostly black hair need to be alert to endocrine and tumor-related diseases, such as pituitary and adrenal tumors, nodules, and occupational lesions that can lead to endocrine hormone secretion disorders in the human body and the illusion of rejuvenation, and other complications such as black hair, increased appetite, hyperactivity, and increased libido. This disease should be ruled out.