The second carbon is connected to the amino group. Amino means there is an NH 2 group bonded to the carbon atom. In the image, you see a + and a -. Those positive and negative signs are there because, in amino acids, one hydrogen atom moves to the other end of the molecule. An extra H gives you a positive charge.
Ranges of normal estrogen levels are measured in parts pg/ml of estradiol. In normal reproductive age women, during the menstrual cycle, estradiol levels range from 50-400 pg/ml. The actual normal level of estrogen varies during different parts of the menstrual cycle. In menopause, the general range may be 10-20 pg/ml.
The reference range estradiol in women varies by menstrual cycle and menopausal status, as follows: 1  Before menopause, estradiol levels are widely variable throughout the menstrual cycle: Mid-follicular phase: 27-123 pg/mL. Periovulatory: 96-436 pg/mL. 2  Following menopause: Under 10 pg/mL.