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antiandrogens p. 676
cirrhosis p. 396
Cushing syndrome p. 352
cystic fibrosis p. 58
ectopic pregnancy and p. NaN
menopause p. 646
Müllerian agenesis p. 640
PCOS p. 664
pituitary adenoma and p. 540
pituitary prolactinomas p. 333
Turner syndrome p. 655
Amenorrhea means no menstruation.
It’s normal before puberty, during pregnancy and lactation, and after menopause.
Sometimes though, menstruation either never starts, which is called primary amenorrhea, or suddenly stops in a person who’s previously menstruating, which is called secondary amenorrhea.
Now, menstruation, and the menstrual cycle as a whole are controlled by the hypothalamus and the pituitary gland, all the way up in the brain.
The hypothalamus secretes gonadotropin-releasing hormone, or GnRH, which makes the nearby anterior pituitary gland release follicle-stimulating hormone, or FSH, and luteinizing hormone, or LH.
In the first two weeks of a normal 28-day cycle, the ovaries go through the follicular phase, meaning that out of the many follicles scattered throughout the ovaries, a couple of them enter a race to become the dominant follicle, that will be released at ovulation.
All the developing follicles secrete loads of estrogen, which negatively inhibits pituitary FSH.
In the meantime, the uterus goes through two phases: the menstrual and proliferative phase.
During the menstrual phase, the functional layer of the endometrium is shed and eliminated through the vagina, leading to menstruation, which lasts an average of five days.
It’s followed by the proliferative phase, during which the rising levels of ovarian estrogen make the functional layer of the endometrium thicken and sprout endometrial glands.
Amenorrhea is the absence of menstrual periods in women during reproductive years. There are two types of amenorrhea: primary and secondary. Primary amenorrhea is when periods have never started by the time a girl reaches 16 years old. Secondary amenorrhea is when periods have stopped for at least three months, even if they had started in the past.
There are many possible causes of amenorrhea, including pregnancy, hormone problems, problems with the ovaries or uterus, eating disorders, excessive exercise, and stress.
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