Sex Hormones During Life Flashcards
What is the definition of puberty?
Maturation of reproductive organs
Production of sex steroids
Develop secondary sexual characteristics
Attain capability to reproduce
How is progression through puberty measured?
Tanner staging
Thelarche- girls - beast development
Testicular volume - boys
Pubarche - pubic hair - both (this is really cause by adrenal androgen production but it goes along with puberty)
What are the secondary sexual characteristics of girls? And order?
Caused by oestradiol
Breast development
Hair growth (public, axillary)
Sweat gland composition- skin oiliness/ acne
Changes to external genetalia
First breast, then growth spurt, then pubic hair. Finally a little bit later menarche
What are the secondary sexual character of boys? And order?
Caused by testosterone
Deepening of voice
Hair growth (pubic then axillary, facial)
Sweat gland composition - oiliness/acne
Changes to external genetalia
First testicular volume, then growth spurt, then pubic hair, finally spermarche
What are the ages of puberty?
Girls: 8-14
Boys: 9-14
Precocious puberty is more common in girls
Delayed puberty is more common in boys
What are the hormone changes during puberty?
ADRENRCHE
Girls: large increase in DHEA
Boys: smaller increase in DHEA
GONADARCHE
Girls: large increase in oestradiol also a large increase in FSH
Boys: large increase in testosterone also a small increase in LH
How does GnRH secretion change with puberty?
In childhood the HPG axis is quiesced
Around puberty there is increased nocturnal GnRH pulsatility
At adulthood there is normal pulsatile GnRH secretion
What is mini puberty?
In a foetus there are high levels of GnRH
This causes testicular descent, penile length, Sertoli cell maturation and behavioural effects
But this is then quiesced until actual puberty
What is menarche?
The start of the menstrual cycle
Occurs ~2.3 years after thelarche, and soon after peak height velocity (growth spurt)
The mean age of onset is 12.7 years but it ranges from 10.7 - 16.1
What are primary and secondary amenorrhoea?
Primary: when you haven’t got your period by 16 tears old
Secondary: when you have it but then lose it for a period of 3-6 months
Most common cause of secondary amenorrhoea is pregnancy
There is also oligomenorrhoe - irregular or infrequent periods
What are the three stages of the menstrual cycle?
Follicular
Ovulation
Luteal
What happens during the follicular phase of the menstrual cycle?
- FSH levels rise
- 2-3 follicles start to grow
- These produce E2 and inhibin B
- These reduce FSH by negative feedback
- This restricts the “FSH” windows so that the non dominant follicules undergo atresia
- A dominant “graafin” follicular emerges
- E2 continues to increase
- There is a switch to positive feedback on LH due to high E2
- This induces a leutenising hormone surge
- Causes ovulation n
What happens in the menstrual cycle after ovulation?
The follicule develops into the corpus leuteum which releases progesterone and oestradiol
Without presence of a fertilised egg, these levels will drop back down by day 28
What is the uterine cycle?
How the endometrium changes during the menstrual cycle
Menstrual phase: bleeding. Layer is shed
Proliferative phase: endometrial lining regrows. New epithelial cells and gland proliferation. Increase in storms and arterioles
Secretory phase: transformation to be receptive for implantation. Increased volume of stromal cells, thick spongy lining. Cork screw shaped glands secreting glycogen, coiling and lengthening of spiral arteries
How does the presence of an embryo affect the menstrual cycle?
During the luteal phase it will secrete beta hCG
This acts in LH receptors on the corpus leuteum, stimulating it to keep releasing progesterone
As progesterone levels don’t drop, the endometrium is not shed for the next cycle
What happens if GnRH secretion isn’t pulsatile?
This decreases LH and FSH secretion
How does GnRH pulsatility change during the menstrual cycle?
Follicular phase: pulse every 90-120 mins
Luteal phase: pulse every 180-240 mins
What is hypogonadism?
Decreased oestrogen in a woman
Decreased testosterone in a man
What is primary hypogonasism?
Low oestradiol (E2)/ testosterone
But high LH/FSH due to reduced negative feedback to the hypothalamus and pituitary
The problem is in the gonads
In men this may be caused by infection (mumps), trauma, cancer of the testes
In women the main cause is menopause (this also has low inhibin)
What is secondary hypogonadism?
Low E2/ testosterone
But also low (or normal) LH/FSH
This is due to a lack of functioning negative feedback
If there are sex hormones the levels of gonadotrophs should deffo be raised, not normal
The problem is in the hypothalamus or pituitary
May be caused by a pituitary tumour or high prolactin
What are the symptoms of menopause?
Due to a lack of oestradiol (occurs at ages 41-55)
Skin dryness/ hair thinning
Hot flushes, sweating, sleep disturbance
Mood disturbance
Osteoperosis (E2 stimulates osteoblasts)
Sexual dysfunction (vaginal dryness, decreased libido)
Weight gain
Amenorrhoea
Cessation of fertility
Climacteric (irregular periods in years close to menopause)
It can be treated with hormone replacement therapy. Oestrogen stimulates the endometrium (of endometrium is intact add progesterone to prevent hyperplasia or cancer)
What are ovarian reserve markers?
Such as anti mullerian hormone
This usually peaks in early adult life and is very low at menopause
So by measuring levels of this, you can see how close a person is to menopause and therefore roughly how many eggs they have
What is early menopause?
Premature ovarian insufficiency (used to be called premature ovarian failure)
Conception can still happen in 20% of people
It can be diagnosed with high FSH levels
Caused by: autoimmune, genetic (fragile X syndrome/ turners), cancer therapy
Is there an equivalent of menopause In men?
“Andropause”?
Sorta
In some people there is late onset hypogonadism
In which the levels of testosterone in the body slowly fall until they are very old
This happens as you get older as levels of sex hormone binding globulin increase. So there is less free T
How is testosterone present/carried in the body?
60% is bout to sex hormone binding globulin (SHBG). This is strongly bound and unavailable
38% is bound to albumin. This is weakly bound and “bioavaliable”
2% is free testosterone. This is active
When should you measure testosterone levels?
In the morning as it has a diurnal rhythm
Also fasting, as T levels can fall with sugar consumption
What are some symptoms of testosterone deficiency?
Sexual dysfunction (low libido)
Erectile dysfunction (includes loss of early morning erections)
Less hair growth (may need to shave less often)
Low energy levels
Mood disturbance
Body composition (increased fat, reduced muscle mass)
Less spermatogenesis
Osteoperosis
What happens to testosterone? (Possible pathways)
Testosterone —> oestrogens (by aromatase enzymes)
This is stimulated by age, obesity, alcohol, insulin, ginadotrophins.
It occurs in adipose tissue, adrenal glands, ovaries (granulosa), testes (sertoli), brain bone and skin
Testosterone —> di hydro testosterone (by 5 alpha reductase)
This occurs in the testes (seminal vesicles and epididymis), prostate, skin and scalp, liver
It is a more potent ligand for androgen receptor
