Anovulatory cycle In other cases, menstruation may be fairly regular (eumenorrhea), or more frequent (intervals < 21 days), or there may be a loss of menstrual pattern (menorrhagia, dysfunctional uterine bleeding). Normal menstrual bleeding in the ovulatory cycle is a result of a decline in progesterone due to the demise of the corpus luteum. It is thus a progesterone withdrawal bleeding. As there is no progesterone in the anovulatory cycle, bleeding is caused by the inability of estrogen — that needs to be present to stimulate the endometrium in the first place — to support a growing endometrium. Anovulatory bleeding is hence
Pharmacokinetics of progesterone of the menstrual cycle with LC–MS/MS are 6.7 to 22.2 ng/mL. When the unreliable method of standalone RIA has been used to measure progesterone levels with oral progesterone, far higher peak levels of 6.5 to 10.2 ng/mL, 13.8 to 19.9 ng/mL, and 32.3 to 49.8 ng/mL have been erroneously observed after single 100, 200, and 300 mg doses, respectively. In addition, progesterone levels have been inaccurately measured by RIA as remaining elevated for 12 to 24 hours. Regardless of assay method, peak levels of progesterone following a dose of oral progesterone occur after about 1 to 3 hours. The elimination