A thin endometrium can lead to the absence of menstruation. Under normal circumstances, the endometrial thickness gradually thickens with the menstrual cycle. Some women have a thin endometrium all the time, without significant thickening, which may manifest as delayed menstruation or even no menstruation. Patients need to visit a hospital to check female sex hormone six and thyroid function, combined with medical history, to find the cause of thin endometrium.1. Endocrine factors: endocrine diseases such as hyperprolactinemia, abnormal thyroid function and premature ovarian failure can inhibit ovarian function, leading to a decrease in estrogen and progesterone, thinning of the endometrium, and always no menstruation. In case of hyperprolactinemia, which is characterized by elevated blood prolactin, treatment with bromocriptine is needed; premature ovarian failure can also lead to a decrease in estrogen and progesterone and thinning of the endometrium, and estrogen and progesterone replacement therapy needs to be given, and menstruation will come regularly after replacement therapy; 2. Endometrial damage: Related to uterine operations such as curettage and abortion, these uterine operations can damage the endometrium, leading to thinning of the endometrium and absence of menstruation. High doses of estrogen and progestin cycle replacement therapy need to be given to thicken the endometrium. If the treatment is effective, the endometrium will thicken and menstruation will be normal. If the treatment is ineffective, further hysteroscopy is needed to check whether uterine adhesions occur and hysteroscopic release of uterine adhesions is required.