The common causes of hair loss on the top of the head are: seborrheic alopecia, baldness, and skin lesions on the scalp area. Seborrheic alopecia, also known as androgenetic alopecia, is mainly caused by the high secretion of androgens in the body. When estrogen secretion in the body is high, estrogen acts directly on hair follicles to destroy them, thus causing hair loss. Women mainly show thinning hair on the top of the head, while men show thinning hair on the top of the head with a significantly receding hairline. If there is a patch of hair loss on the top of the head but the scalp is normal, this is usually called baldness, which is mainly affected by immune factors, genetic factors, emotions, and emergency events. If there is a skin lesion on the top of the head, such as trauma causing damage to the hair follicles, lichen planus on the top of the head, or scleroderma, it can cause hair loss on the top of the head, and treatment is needed to address the cause when hair loss occurs on the top of the head.