What is premature ovarian insuffeciency?

Clinical signs: hot flashes, estrogen deficiency. Hormonal expression: LH and FSH raised with explosive LHRH, estradiol decreased <30, progestogen test negative Etiologies (induced early menopause (ovariectomy, chemotherapy, radiotherapy) , spontaneous early menopauses (autoimmune ovaritis- may be associated with other auto immune diseases))