LMP301 Lecture 10: Infertility Flashcards
Infertility
Define: infertility
failure to conceive after 1 year of regular, unprotected sex
% distribution of factors that cause infertility
40% male
50% female
10% unknown
1/3 of the female causes for infertility is due to…
This is ___ in males.
endocrine abnormalities (hormones)
Rare
Sources of sex hormones
- Gonads (testis, ovary)
- Peripheral conversion (adrenal gland, adipose tissue)
DHEA and DhEA is produced by…
adrenal cortex
source of testosterone in women
1/2 from ovary
1/2 from peripheral conversion (DHEA & DHEAS)
DHEAS is a differential marker for…
excess androgen production in women (problem at ovaries and adrenal gland)
What are the sex hormones?
- Testosterone
- Androgens
- Estradiol
- Estrogens
- Sex hormone binding globulin (SHBG)
SHBG
Sex hormone binding globulin
SHBG has higher affinity for… than …
testosterone
estradiol
___ stimulates SHBG synthesis in the liver thought…
Estradiol
gene regulation
_____ inhibits SHBG synthesis
testosterone
concentration of SHBG in females vs. males
2x as much in females
Factors which alter [SHBG] also alter…
ratio of unbound testosterone to unbound estradiol
What hormones are needed for spermatogenesis and virilization to occur?
- Hypothalamus: GnRH
- a. pituitary: FSH + LH
- FSH -> spermatogenesis
- LH -> testosterone -> dihydrotestosterone & virilization
Feedback system for FSH in male
Inhibin neg feedback on a. pituitary
Activin pos feedback on a. pituitary
Feedback system for LH in male
Testosterone neg feedback on a. pituitary and hypothalamus
Dihydrotestosterone functions
- important for male fetus development
- development of sex organs for males
- more potent than testosterone
DHT
Dihydrotestosterone
Testosterone -?-> DHT
5a-reductase
testosterone can be converted into…
- DHT
- Estradiol
testosterone -?-> estradiol
aromatase
Disorders of male sex hormones
- Hypogonadism
- Defects in androgen action
Hypogonadism is divided into…
- primary
- secondary
- tertiary
Primary Hypogonadism
= hypergonadotropic hypogonadism
= testicular failure
hypergonadotropic because low testosterone causing other signals to be high
Primary Hypogonadism defects are due to…
- congential
- acquired
secondary + tertiary hypogonadism
= hypogonadotropic hypogonadism
hypogonadotropic because source of problem
Causes of secondary + tertiary hypogonadism
- pituitary tumours
- hypothalamus disorders
Example of a hypothalamus disorder that may cause secondary + tertiary hypogonadism
Kallmann’s syndrome (GnRH deficiency)
Defects in androgen action is divided into…
- testicular feminization syndrome
- 5a-reductase deficiency
testicular feminization syndrome is also known as…
androgen insensitivity syndrome
testicular feminization syndrome
The androgen receptor doesn’t work
5a-reductase deficiency
- DHT deficiency (testosterone can’t be converted to DHT due to lack of 5a-reductase)
- only affect chromosomal 46XY males (no females are affected)
- can’t develop testes
- males look like females
If sperm analysis of males is normal, what can be ruled out?
endocrine disorder for infertility
If sperm analysis of males is abnormal, what is next measured?
- testosterone
- FSH
- LH
- prolactin
high prolactin in males
hyperprolactinemia
Low testosterone & low gonadotrophins in males
Hypogonadotrophic hypogonadism
If GnRH is low, cause is tertiary
If GnRH is normal, cause is secondary
gonadotrophins
FSH
LH
Low testosterone & high gonadotrophins in males
Testicular failure
When GnRH pulses fast, what is released from the a. pituitary?
LH
When GnRH pulses slow, what is released from the a. pituitary?
FSH
Female: FSH stimulates…
follicle growth
Female: LH stimulates…
- ovulation
- corpus luteum
Feedback of FSH in female
neg feedback by inhibin B (secreted by follicle growth)
neg feedback by inhibin A and estradiol (secreted by ovulation & corpus luteum)
Feedback of LH in female
neg feedback by progesterone & testosterone (secreted by ovulation & corpus luteum)
- this also neg feedbacks on GnRH
pos feedback by inhibin A and estradiol (secreted by ovulation & corpus luteum)
Relationship between estrogen and LH / FSH
LH: positive feedback: as estrogen increases, LH will too
FSH: neg feedback: as estrogen increases, FSH decreases
When does the slow FSH rise occur?
When menses begins (late luteal - early follicular)
___ is secreted after ovulation, and if pregnancy occurs, will continue to be high. However, if menses occurs, it will fall.
Progesterone
What causes the LH peak?
pos feedback on LH by ovarian steroids
what causes the slow FSH rise?
Neg feedback on FSH by estradiol & inhibin
FSH rise indicates…
next wave of follicular maturation (new cycle)
What are the indications of ovulation?
- Progesterone rise
- Increased body temp
- LH surge estimates when ovulation occurs
- Ultrasound detection of maturing follicle & ovulation
Disorders of female sex hormones
- hypogonadism
- amenorrhea
- Hirsutism
hypogonadism is divided into…
- Primary
- Secondary
- Tertiary
Primary hypogonadism
hypergonadotropic hypogonadism
= ovarian failure
- ovaries can’t produce enough estrogen
- feedback causes high LH/FSH
Secondary & tertiary hypogonadism
Hypogonadotropic hypogonadism
- problems with a. pituitary
- problems with hypothalamus (Kallmann’s syndrome)
amenorrhea is divided into…
- primary
- secondary
- oligomenorrhea
Primary amenorrhea
Didn’t establish spontaneous periods by the age of 16
secondary amenorrhea
Had period before, but somehow stopped for >6 months
Examples of primary amenorrhea
- resistant ovary syndrome
- Kallmann’s syndrome
resistant ovary syndrome is a problem at…
FSH receptor
Examples of secondary amenorrhea
- pregnancy
- hyperprolactinemia
- PCOS
Oligomenorrhea
Irregular, infrequent periods (< 9 times per year)
Hirsutism
- female with male body hair
- due to genetics or idiopathic
- mostly caused by PCOS if severe
PCOS
polycystic ovarian syndrome
What is the first thing to look at when examining infertility in women?
Regular periods?
regular vs. amenorrhea / oligomenorrhea
If a women’s period is normal, what is measured next? Outcome?
Progesterone to determine if she is ovulating
- ovulating = no problem
- measure FSH, LH, prolactin if she isn’t
In a women with abnormal periods, what is next tested? Outcome?
Screening for pregnancy
- Pos = pregnant = no problem
- Neg = not pregnant = go on to test LH, FSH, prolactin
High prolactin in women
Hyperprolactinemia
high FSH, high LH in women
ovarian failure (primary)
low FSH, high LH in women
PCOS
test LH, FSH, prolactin all normal
Further investigation (maybe side effect of another disease)
Low FSH, low LH in women
Hypogonadotropic hypogonadism (secondary or tertiary)
PCOS symptoms
- many small cysts in ovaries
- menstruation, but not always ovulate
- infertility
- hirsutism
- obesity
- irregular menstruation
- hyperinsulinemia
- insulin resistance
PCOS is thought to be caused by…
- hypothalamic disorder
- genetics
PCOS does not involve diseases in…
- adrenal gland
- pituitary gland
Biochemical characteristics of PCOS
- high serum estrogens
- (pos feedback) high LH
- (neg feedback) low FSH
- high serum testosterone (free & total)
- decreased SHBG
- high DHEAS
Why does ovulation not occur in PCOS?
LH surge continues to be high. Ovulation typically occurs after LH peaks and DROPS