Sex Hormones Flashcards
What is the definition of puberty?
Maturation of Reproductive Organs
Production of Sex-Steroids E.g. Oestradiol / Testosterone
Develop Secondary Sexual Characteristics
Attain capability to Reproduce
What is breast development called in girls?
Thelarche
What increases in boys genitalia during puberty?
Testicular volume
seen with a prader orchidometer
What is pubic hair growth called and who does it occur with?
Pubarche
both
stages I-V
What is gonadarche?
Gonadarche - Activation of gonads by HPG axis
What is menarche?
Menarche - Menstrual Cycles
What is spermarche?
Spermatogenesis
What is adrenarche?
Adrenarche - Adrenal Androgen Production (starts ~2yrs before Gonadarche)
What is pubarche?
pubic hair
what does -arche mean?
onset of
What are secondary sexual characteristics of girl in puberty?
Oestradiol:
Breast Development
Hair Growth - Pubic, Axillary
Sweat Gland Composition - Skin oiliness / Acne
Changes to external genitalia
What are secondary sexual characteristics of boys in puberty?
Testosterone:
Deepening of Voice
Hair Growth - Pubic then Axillary, facial
Sweat Gland Composition - Skin oiliness / Acne
Changes to external genitalia
What is the sequence of pubertal events in girls?
onset 8-13 y/o
What is the sequence of pubertal events in boys?
onset 9-14 y/o
tanner= development
What is the 1st and late sign of puberty in girls?
1st sign is thelarche
late sign is menarche
What is boys testicular size prepubertal and adult size?
Prepubertal < 4mls
Adult Size > 15mls
what are DHEAS/ DHEA?
adrenal androgens
What is the relationship between gonadarche (activation of HPG axis) and FSH and LH serum levels?
How do DHEA levels change between boys and girls and their ages?
Why is adrenaline more important fro girls?
Because boys make testosterone which is an androgen so they can still make pubic hair etc.
How would you describe normal GnRH secretion?
pulsatile secretion
What are the targets for LH and FSH?
FSH (follicle stimulating hormone)= Ovaries / testes (tubules)
LH (luteinizing hormone)= Ovaries / testes (Leydig cells)
How are LH and FSH linked to oestrogen?
Positive feedback triggers the anterior pituitary to release more FSH and LH. More FSH and LH cause the ovary to produce more estrogen. the ensuing LH surge is responsible for ovulation.
What is the hormonal control of puberty, and how does it change from childhood to adulthood?
Gonadarche
Childhood= quiescence/ inactivity of HPG axis
Puberty= Increased nocturnal GnRH pulsatility
Adult= Normal GnRH secretion
What happens between foetal and infanthood?
mini puberty
testicular descent
penile length
sertoli cell maturation
behavioural effects
What counts as an abnormal onset of puberty?
Mean +/- 2.5 SDs
Precocious or Delayed
In who is delayed more common and in who is precocious more common?
Boys delayed is more common
Girls precocious is more common
When is menarche?
roughly 2.3 years after thelarche
soon after Peak height velocity (PHV)
mean age is 12.7 years old (range 10.7-16.1)
When is it considered abnormal to have your first period later than?
later than 16
primary amenorrhoea
For how long is it common for your first period to be irregular?
irregular / anovulatory for first 18 months
What is secondary amenorrhoea?
Periods start but then stop for at least 3-6 months
- most common reason is pregnancy in young women
How long is a menstrual cycle?
28 days (24-35)
+/- 2 days each month
What are the types of menorrhoea?
a-menorrhoea- absence of periods
oligo-menorrhoea- few periods
What is amenrrhoea?
- No periods for at least 3-6 months
- or up to 3 periods per year
What is oligomenorrhoea?
- Irregular or Infrequent periods >35 day cycles
- or 4-9 cycles per year.
What are the phases of the menstrual cycle?
Follicular phase
Ovulation phase
Luteal phase
What are the stages of the menstrual cycle? (follicular and pre-ovulatory phase)
Follicular Phase:
1. Follicle stimulating hormone (FSH) rises.
2. 2-3 follicles start to grow.
3. Produce E2 and Inhibin B.
4. These reduce FSH (by -ve feedback).
5. Restrict ‘FSH window’ and non-dominant follicles undergo atresia.
Follicular Phase (Pre-Ovulatory phase):
6. A dominant ‘Graafian’ follicle emerges.
7. E2 continues to increase.
8. Switch to +ve feedback by high E2.
9. Induces luteinising hormone (LH) Surge.
10. Causes ‘Ovulation’
What happens during ovulation?
egg released from follicle
rest of follicle becomes corpus luteum
What happens during the luteal phase?
Midluteal D21 progesterone= evidence of ovulation
- prepares endometrium for implantation
What are the stages of the endometrium “uterine cycle”?
Menstrual phase
Proliferative phase (oestradiol)
Secretory phase (progesterone)
What is needed to maintain uterus lining?
one of the things is LH
What acts on Lh receptors?
B-hCG
Human chorionic gonadotropin is a hormone produced primarily by syncytiotrophoblastic cells of the placenta during pregnancy. The hormone stimulates the corpus luteum to produce progesterone to maintain the pregnancy.
also secreted by embryo tissue/ blastocyst
What does continuous non-pulsatile administration of GnRH cause?
decreased LH/ FSH secretion
What is hypogonadism?
Hypogonadism is Decreased Oestrogen in a Woman / Decreased Testosterone in a Man
What is 1ary, 2ary, 3ary hypogonadism?
1ary= O/T is not being made for ovaries or testes
2ary= not being made by pituitary gland
3ary= not being made by hypothalamus
What is GnRH pulsatility during the menstrual cycle?
Every 90-120mins in follicular phase
every 180-240mins in luteal phase
What is primary hypogonadism and what can cause it?
Primary Hypogonadism
High LH / FSH
Low E2 / Testo
Men - Eg Infection/ Trauma / Cancer of Testes
Woman - Menopause
What is secondary hypogonadism?
Secondary Hypogonadism/ hypogonadotropic hypogonadism
Eg Pituitary Tumour, High Prolactin
Low (or normal) LH / FSH Low E2 / Testo
What are symptoms of menopause?
Lack of Estradiol
Skin Dryness / Hair Thinning
Hot Flushes / Sweating / Sleep Disturbance
Mood Disturbance
Osteoporosis - Decreased Bone Mineral Density (BMD)
Joint Pains
Sexual Dysfunction - Vaginal Dryness, Decreased Libido
Genito-urinary disturbance
Weight gain
Amenorrhoea – Peri- leading up to menopause, Post- after 1yr
Cessation of fertility
What is treatment for menopause?
Menopausal Hormone Therapy (MHT):
previously known as HRT (Hormone Replacement Therapy)
Oestrogen Replacement -
Oestrogen stimulates the endometrium to proliferate
Add Progesterone - if Endometrium is intact to prevent risk of Endometrial Hyperplasia / Cancer (progesterone breaks down the lining)
What is an example of an ovarian reserve marker?
Anti-mullerian hormone (AMH) secreted by granulosa cells in ovaries
Peaks in early adult life
Very low at menopause
What age does menopause occur?
range 45-55 y/o
median= 51 y/o
Only 1% premature <40 y/o
What is early menopause called?
Premature ovarian insufficiency
What is premature ovarian insufficiency (POI)?
Same Symptoms as Menopause
- Previously called ‘Premature Ovarian Failure’ POF
- Conception can happen in 20%.
- Diagnosis High FSH >25 iU/L (x2 at least 4 wks apart)
Causes:
- Autoimmune
- Genetic eg Fragile X Syndrome / Turner’s Syndrome (XO)
- Previous Cancer therapy eg Radio- or Chemo-therapy
Is there an andropause?
What is the testosterone ‘free hormone’ hypothesis?
Binding of total testosterone in circulation
Albumin 38%
- weakly binds testosterone ‘bioavailable’
Active 2%
- free testosterone
SHBG 60%
- strongly binds testosterone unavailable
- SHBG bound testosterone
What is SHBG?
sex hormone binding globulin
What type of rhythm does testosterone have?
Diurnal rhythm
Testosterone is higher in the morning
measure it before 11am- ideally measure with fasting as it can fall roughly 20% with sugar
What are the symptoms of testosterone deficiency?
Sexual Dysfunction - Reduced Libido (sexual desire) Erectile Dysfunction»_space; loss of Early Morning erections
Hair Growth - Frequency of Shaving?
Energy levels - General Well-being, Fatigue.
Mood Disturbance
Body Composition - Increased Fat / reduced Muscle Mass Gynaecomastia (breast enlargement in man)
Spermatogenesis - High levels of Intratesticular testosterone needed
Bone health - (Via conversion to oestrogen)
What is the local tissue effect of testosterone?
Di-hydro-testosterone is a more potent ligand for androgen receptor
What is the role of di-hydro-testosterone (google)?
During embryonic life, it is involved primarily in the sexual differentiation of organs. Through adolescence and adult life, DHT promotes prostate growth, sebaceous gland activity, male pattern baldness, and body, facial and pubic hair growth.
A 25 year old man presents with low libido. On examination he has normal secondary sexual characteristics. Testicular volume is 15 mL bilaterally.
What could be the cause of his low libido?
Primary hypogonadism
What are male secondary sexual characteristics?
deepening of voice
Hair growth- pubic then axillary, facial
Sweat gland composition- skin oiliness/ acne
Changes to external genitalia
A 25 year old man presents with low libido. On examination he has normal secondary sexual characteristics. Testicular volume is 15 mL bilaterally.
What investigations would you perform and how would these help you?
testosterone levels (before 11am)
LH and FSH levels (these would be high with primary)
What is the difference between testosterone and dihydrotestosterone?
dihydrotestosterone is more potent and binds to androgen receptors with higher affinity
