10/16- Disorders of the Ovary and Female Reproductive Tract Flashcards
Describe the genetics influencing ovary development
- No gene generates an ovary from an undifferentiated gonad
- It is the absence of SRY (sex determining region Y aka testis-determining factor)
Describe formation/maturation of the ovary
- Embryological origin?
- Primordial germ cells migrate to the genital ridge -> primary oocytes
- Remainder of female reproductive organs formed from the paramesonephric (Müllerian) ducts in the absence of AMH
- Recall, AMH formed by Sertoli cells in testes
What are the Mullerian structures?
?
- Uterus
- Fornix
- Upper 1/3 of vagina
What hormones do the ovaries produce?
- Pathway of these hormones/conversion
Ovaries:
- Vast majority of estrogens and
- 1/3 of circulating testosterone
- And contribute to another 1/3 of T by generating androstenedione)
- Peripheral conversion of this ovarian androstenedione and adrenally produced androstenedione and DHEAS results in the other 2/3 of circulating testosterone
Describe the hormones behind the menstrual cycle
- Hypothalamus secretes GnRH (pulsatile)
- GnRH stimulates pituitary to secrete LH and FSH
- LH and FSH trigger ovulation
- The ovaries secete hormones that act on the endometrial lining and feed back to the hypothalamus and pituitary
- GnRH pulsatility (90-120 min) -> FSH -> estradiol -> inhibits FSH
- Estradiol -> increases GnRH pulse frequency to 60 min -> LH
- Estradiol -> directly on pituitary -> LH
- LH -> ovary -> estradiol -> increases pituitary sensitivity to GnRH -> LH surge -> ovulation
- Ruptured follicle (corpus luteum) -> progesterone -> reduces GnRH pulse frequency
What is primary amenorrhea?
- Secondary?
- Hypomenorrhea?
- Primary amenorrhea: the delay of menarche beyond the age of 16, or, in the absence of secondary sexual characteristics, beyond age 13
- Secondary amenorrhea: is a condition in which menstruation begins at the appropriate age, but later ceases for 6 or more months in the absence of normal causes such as pregnancy, lactation, or menopause.
- Hypomenorrhea: a diminution in the quantity of menstrual flow based on tampon or napkin requirement
What is hypermenorrhea?
An increase in duration, quantity or both of menstrual flow that occurs at normal cycle intervals
What is oligomenorrhea?
A recurrent prolongation of intermenstrual intervals leading to a decreased frequency of menses (fewer than 6 to 8 per year).
What is polymenorrhea?
A menstrual flow that is near normal in quantity and duration but which occurs too frequently
What is anovulation?
Most common cause of amenorrhea during the reproductive years
- Differs from ovarian failure in that oocytes remain in the ovary
What can cause amenorrhea?
(Go up/down hypothalamic/pituitary/gonadal axis):
- Hypothalamic defects (estrogen deficient state)
- Pituitary defects (estrogen deficient state)
- Ovarian failure (estrogen deficient state)
- Anovulation despite adequate estrogen
- Outflow tract disorders (anatomical)
What hypothalamic disorders could result in amenorrhea?
- Isolated GnRH deficiency
- Functional hypothalamic amenorrhea
- Tumors (craniopharyngioma, metastatic carcinoma, lymphoma)
- Infiltrative
- Sarcoidosis
- Histiocytosis
- Hemochromatosis
What causes isolated GnRH deficiency?
- Genetics
- Pathogenesis
- Symptoms
- Treatment
Several genetic lesions, most famously Kallman’s syndrome
PATHOGENESIS
- GnRH neurons originate from the olfactory area during embryogenesis
- GnRH and olfactory neurons migrate together along cranial nerves connecting the nose and forebrain to the hypothalamus
- Mutations that affect this migration result in hypogonadotropic hypogonadism and anosmia
- Kal-1 and FGFR1
GENETICS
- Mostly sporadic, some familial
- Mostly XLR (AD and AR patterns much less common)
Treatment: replace hormones to stimulate secondary sex characteristics and bone density
What is going on in Functional Hypothalamic Amenorrhea?
- Causes
- Responsible for 15-35% of amenorrhea cases
- Reduced GnRH drive -> low/low-normal serum levels of FSH and LH -> anovulation
Causes:
- By definition, no pathologic disease; no organic anatomic problem
- Possibly mediated through leptin (an adipocyte hormone)
- Anorexia or extreme exercise
- Associated with hypercortisolemia
- Mild hypercortisolemia can be induced by extreme psychological distress, anorexia… (not Cushing’s levels)
What are risk factors for Functional Hypothalamic Amenorrhea?
- Eating disorders (anorexia nervosa)
- Exercise
- Psychological stress/perfectionism
- Weight (> 10% below IBW)
- Nutritional deficiencies (severely reduced fat intake)
- “Female athlete triad”
- Disordered eating
- amenorrhea
- Osteoporosis
Treatment for Functional Hypothalamic Amenorrhea?
- Cognitive behavioral therapy for stress
- Returning BMI to normal