Because FSH has a longer half life than LH (4 hrs vs 30 mins).
Why are Androstenedione and Testosterone reduced?
Adrenal gland is now the only source of androstenedione
while total testosterone is reduced because there is less conversion from androstenedione, the amount of testosterone secreted from the ovarian stroma is increased because of the elevated levels of FSH and LH.
Why is the androgen:estrogen ratio increased?
Peripheral conversion of androstenedione to estrogen is now the principal source of estrogen. Though this may be significant (especially in women with
Ý body weight due to aromatization of fat to androgens), it does not compare to the estrogen levels previously produced by ovary
eventually ovarian stroma is exhausted and no longer responds to FSH/LHÞ steroidogenesis stops
with age, adrenal production of estrogen precursors becomes insufficient to sustain 2o tissues
Short-term Symptoms of Menopause
Disturbances in menstrual pattern
anovulation in pre-menopausal women, extragonadal endogenous estrogen, or estrogen administration in post-menopausal women may cause dysfunctional uterine bleeding due to excessive estrogen unopposed by progesterone; raises concern of endometrial neoplasia
"hot flashes" are the hallmark of menopause, experienced to some degree by most women
"hot flash" sudden onset of reddening of skin over head, neck, and chest, accompanied by feeling of intense body heat and concluded by profuse perspiration
hot flash duration seconds-minutes (rarely an hour); frequency can be rare or every few minutes
more severe at night and stress, less severe in cool environment
50-75% of women get hot flashes for 1-2 years, with rest > 5 years.
Physiology of Hot Flash
Not understood. Probably originates in hypothalamus as result of declined estrogen
Coincides with surge of LH (not FSH) but not dependent upon LH; same hypothalamic event that causes hot flashes also stimulates elevated LH (via GnRH)
atrophy of mucosal surfaces; accomp.by vaginitis, pruritus, dyspareunia (pain during intercourse), stenosis
mucosal thinning of urethra and bladder; leads to urethritis with dysuria, urgency, incontinence, Ý urinary frequency
- ß skin collagen and ß skin thickness.
Fatigue, nervousness, headaches, insomnia, depression, irritability, joint and muscle pain, dizziness, and palpitations are associated with early post-menopause
hot flashes during sleep may disturb REM sleep leading to emotional instability during wake hours
Long-term Consequences of Menopause
Progressive loss of bone mass leading to Ý in fractures
after menopause up to 5% of trabecular bone and 11.5% of total bone mass lost per yr (slower in African-Americans)
risk of fracture depends on bone mass at time of menopause and rate of bone loss following menopause.
bone mass with: Ý age, ß parity, early menopause, race (white>black), small frame, family history, lack of physical activity, smoking, EtOH, caffeine