Reproductive endocrinology

Question 1

Gonadotropin-releasing hormone (GnRH)

Answer 1

produced in hypothalamus in pulses

stimulates secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH) by the anterior pituitary

Question 2

Luteinizing hormone (LH)

Answer 2

Males:promotes synthesis of testosterone by Leydig cells of the testes
negative feedback of testosterone on hypothalamus and pituitary
Females: ovulation

Question 3

Follicle stimulating hormone (FSH)

Answer 3

stimulates spermatogenesis by Sertoli cells of the testis
sertoli cells produce inhibin –> negative feedback on anterior pituitary
females: act on ovaries, negative feedback through estrogen and progesterone

Question 4

Testosterone

Answer 4

circulates bound to protein Sex Hormone Binding Globulin (SHBG)
Converted in target tissues to dihydrotestosterone (DHT) by 5a-reductase

Question 5

DHT

Answer 5

a more potent androgen than testosterone

Question 6

Androgen resistance

Answer 6

rare genetic disorder due to lack of testosterone receptor or deficiency of 5a-reductase
result: high testosterone level, low DHT

Question 7

Primary Hypogonadism (m)

Answer 7

testes dysfunction
low serum testosterone, high LH/FSH
causes: Kleinfelters, mumps, varicocele (damaged/blocked testicular vein)

Question 8

Secondary hypogonadism (m)

Answer 8

pituitary dysfunction

result: low serum LH and FSH, low testosterone
causes: pituitary damage, tumors in pituitary, loss of pulsatility of GnRH

Question 9

Tertiary hypogonadism (m)

Answer 9

hypothalamus dysfunction

causes: Kalmann- lack of migration of GnRH neurons to hypothalamus during embryonic development

Question 10

GnRH stimulation test

Answer 10

used to differentiate between secondary and tertiary causes of hypogonadism

secondary: pituitary wont respond properly
tertiary: can respond

Question 11

Gynecomastia

Answer 11

breast enlargement in men due to estrogen androgen imbalance

common in alcoholic liver disease and general obesity

Question 12

Androgens from adrenal cortex

Answer 12

androstenedione and DHEA (DHEA-S) in both males and females

Question 13

Estrogen

Answer 13

sex hormone from the ovaries
secreted mainly as estradiol
most estradiol is bound to SHBG

Question 14

Progesterone

Answer 14

sex hormone from the ovaries

most progesterone in serum is bound to albumin

Question 15

3 phases of the 28-day ovulation cycle of the human female

Answer 15

Follicular phase
Ovulatory phase
Luteal phase

Question 16

Follicular phase

Answer 16

FSH and LH levels start to increase –> estradiol production and follicular development

Question 17

Ovulatory phase

Answer 17

estradiol threshold is met –> stimulate increase in LH levels through positive feedback –> ovulation

Question 18

Luteal phase

Answer 18

corpus luteum produces estradiol and progesterone to thicken the uterine lining (endometrium)
day 22: corpus lutem regresses –> fall in estradiol/progesterone –> menstruation

Question 19

Day one is marked by

Answer 19

first day of menstruation

Question 20

If pregnancy occurs

Answer 20

estradiol and progesterone do not fall and continue as per positive feedback

Question 21

Primary hypogonadism (f)

Answer 21

dysfunction of ovaries

result: low serum estradiol, high LH FSH
causes: Turner’s, premature menopause, polycystic ovarian syndrome

Question 22

Secondary hypogonadism (f)

Answer 22

dysfunctoin at pituitary

result: low serum LH FSH, low estradiol
causes: pituitary damage, tumors

Question 23

Tertiary hypogonadism (f)

Answer 23

dysfunction at hypothalamus

causes: Kalmann

Question 24

Hirsutism and virilization

Answer 24

overproduction of androgens –> male pattern of body hair (hirsutism)
masculinization of females from elevated level of androgens (v)

Question 25

Polycystic ovarian syndrome

Answer 25

imbalance of androgens and estrogens –> infertility
may be genetic
treated with insulin sensitizing agens, weight loss, oral contraceptives, anti-androgens

Question 26

Ectopic pregnancy

Answer 26

implantation and growth of the embryo in a location other than the uterus
meausre: serial hCG, less than 66% rise in hCG in 48 hours

Question 27

hCG as tumor marker

Answer 27

for trophoblastic (placental) tumors and non semniferous testicular cancer