The diagnosis of menopause is pretty obvious if a woman is in her late 40s or early 50s, her periods stop, and she has hot flashes. The diagnosis can be more difficult in young women, women with atypical symptoms, or women who have had a hysterectomy. Because thermal abnormalities that could be construed as hot flashes are a symptom of some diseases (thyroid problems and some cancers), the presence or absence of these conditions should be sought. There is a simple blood test which measures circulating follicle-stimulating hormone (FSH) levels. As the ovaries lose the ability to produce estrogen, the pituitary gland increases production of other hormones (called "gonadotropin") to stimulate the ovary to do better. One stimulating hormone is FSH. It is generally accepted that a woman has reached menopause when her FSH blood level rises above 30 to 40 MIU/ml (depending on the testing laboratory). Estrogen (as estradiol or estrone) is also sometimes measured, but obtaining a reliable diagnosis of menopause may be difficult by measuring estrogen alone.