Lack of menstruation for a long period of time could indicate decreased functionality of the ovaries (hypogonadism). Hypogonadism is either primary (problem is located in the ovaries), secondary (in the pituitary gland) or tertiary (in the hypothalamus). Functionally active ovarian cysts can also cause lack of menstruation but usually for a few months. Ultrasound examinations and hormonal analyses (FSH, LH, estrogen, progesterone, prolactin, thyroxin, and testosterone) should be requested to confirm or exclude hypogonadism or ovarian cysts as possibilities for lack of ovulation and infertility.