This is therapy for the failure of the respective organ to produce a certain hormone. It involves the administration of the hormone orally (e.g. L-thyroxine), transdermally (e.g. estrogen), or subcutaneously. In the case of ovarian failure, estrogen is often given transdermally. If the patient has a uterus, concomitant administration of progestrone is needed or else endometrial hyperplasia and adenocarcinoma may be caused by unopposed estrogen.