Hi, everybody. I've been experiencing hot flashes, hair loss, irregular periods, and dry eyes for several months. I had my hormone and thyroid levels tested twice, and, while everything technically came back normal, my estradiol (52 pg/ml) level concerns me. I've read that anything below the 50 pg/ml mark is not a good sign. Is this true? Does this number suggest that I'm in the early stages of premature ovarian failure, or are there other causes of low estradiol?