Sex Hormones Flashcards
Define puberty
Stage where maturation of reproductive organs occurs and sex steroids such as oestradiol and testosterone are produced. Secondary sexual characteristics develop and ability to reproduce is attained.
How does Tanner staging measure stage of puberty
Measures thelarche (breast development) in girls and increase in testicular volume in boys. Measures pubarche for both on a scale of 1-5. The Prader Orchidometer is used to measure testicular volume where above 15ml-25ml is considered adult size.
What secondary sexual characteristics does oestradiol induce?
Breast development, Hair Growth (pubic then axillary), change to sweat gland composition (skin oiliness/acne) and changes to external genitalia.
What secondary sexual characteristics does testosterone induce?
Deepening of voice, Hair Growth (pubic, axillary, facial), change to sweat gland composition (skin oiliness/acne) and changes to external genitalia.
Describe sequence of pubertal events for girls
First sign is thelarche at 10.5 followed by onset of pubic hair at 11. Peak height velocity achieved at 11.4 with menarche at 12.8. Adult breast size reached by 14.6 and adult pubic hair present at 13.7.
Describe sequence of pubertal events for boys
First sign is increase in testicular volume at 11.4. Onset of pubic hair at 12 followed by penile growth at 12.2. Peak height velocity reached at 14.1 with adult genital size achieved by 14.9 and adult pubic hair by 15.2.
What is adrenarche and what does it cause?
Adrenarche is when the adrenal glands begin producing androgens resulting in pubarche.
What is gonadarche?
Activation of HPG axis
What is the GnRH secretion pattern?
Gonadotrophin releasing hormone is released in a pulsatile way through the day from the hypothalamus. Both sexes go through a minipuberty in the neonatal period where there is a spike in GnRH levels. In boys, this allows for testicular descent, penile length, Sertoli cell maturation and behavioural effects. There occurs a quiescence of the HPG axis through childhood until reactivated at puberty where there is an increased nocturnal pulsatile secretion of GnRH. Eventually, GnRH secretion becomes regular at adulthood.
What is considered normal onset of puberty for girls and boys?
For girls, 8-13 years is considered normal age for onset of puberty. Below 8 considered precocious while beyond 14 considered delayed. Precocious onset of puberty more common in girls. For boys, a normal range is between 9 and 14 - delayed puberty more common in boys.
When does menarche usually occur?
Roughly 2.3 years following thelarche and soon after peak height velocity is achieved. Mean age is 12.7 years but ranges from 10.7 to 16.1.
What are the different kinds of amenorrhoea?
Primary amenorrhoea is where menstruation has not occured by 16 years of age. Secondary amenorrhoea is where menstruation has started but has not occured in 3-6 months.
What is amenorrhoea and oligomenorrhoea?
Amenorrhoea is an absence of periods where no period has occured in 3-6 months or has less than 3 periods a year. Oligomenorrhoea is irregular or infrequent menstruation where cycles are longer than 35 days or range between 4-9 cycles a year.
Describe follicular phase
- FSH rises and 2-3 follicles start to grow.
- The Graafian follicle produces E2 and Inhibin B is secreted by granulosa cells
- These reduce FSH (by -ve feedback).
- Restrict ‘FSH window’ and non-dominant follicles undergo atresia.
- Hence, a dominant Graafian cell emerges and E2 continues to increase.
- High E2 levels cause a positive feedback effect on pituitary and hence, LH levels surge causing ovulation.
Describe luteal phase
Corpus luteum secretes progesterone and oestradiol
Describe uterine cycle
Menstrual phase lasts 5-7 days followed by proliferative phase where oestradiol dominates. The endometrial lining regrows and new epithelial cells grow. Glands proliferate and there is an increase in stroma and arterioles. Progesterone dominates in the secretory phase. Here uterine lining transforms to be receptive to implantation. There is an increased volume of stromal cells creating thick spongy lining and cork-screw shaped glands secrete glycogen while spiral arteries coil and lengthen.
What occurs once successful implantation happens?
If successful implanation occurs, embryo will produce b-Hcg which acts on LH receptors on the corpus luteum. This maintains production of oestrogen and progesterone in the first few weeks of pregnancy. If implantation doesn’t occur, corpus luteum dies off and progesterone levels reduce.
How does GnRH pulsatility change during the menstrual cycle?
During follicular phase, pulses occur during every 90-120 mins but during luteal phase, pulses become less frequent occuring every 180-240 mins.
What is primary hypogonadism
Hypogonadism is reduced oestrogen in females and reduced testosterone in males. This is primarily a problem of the gonads as characterised by high FSH and LH levels but low gonad hormones. In men, it is most commonly caused by injury to the testes, cancer of the testes or infection. In women, most common cause is menopause. The high FSH and LH is caused by the reduced negative feedback.
What is secondary hypogonadism
Indicates a problem with the hypothalamus or pituitary gland where a low or normal amount of FSH and LH is produced. Low levels of testosterone and oestrogen. This is caused by a pituitary tumour or high prolactin. Prolactin inhibits release of GnRH.
What happens to hormone levels during menopause?
Low E2, High FSH and LH, Low Inhibin
What are the symptoms of menopause?
Skin dryness/hair thinning
Hot flushes/Sweating/Sleep Disturbance
Mood Disturbance
Osteoporosis - decreased bone mineral density as E2 stimulates osteoblasts
Sexual dysfunction - vaginal dryness, decreased libido
Weight gain
Amenorrhoea - peri within 1 year, post after
Cessation of fertility
Climacteric - irregular periods in years close to menopause
What is treatment for menopause?
Oestrogen replacement - hormone replacement therapy. Oestrogen stimulates the endometrium.
Add progesterone if endometrium intact to prevent risk of endometrial hyperplasia/cancer.
What is the role of anti-Mullerian hormone?
Acts as a marker of ovarian reserve by counteracting effects of FSH, preventing follicle recruitment so it can be preserved for ovulation later. Levels of AMH are a good indicator of resting pool. Peaks in adulthood and decreases from late 20s until very low before menopause. It is produced by granulosa cells in the ovaries.
