Sex hormones Flashcards

1
Q
  • Define puberty
A

Maturation of Reproductive organs (ovaries and testes)

Production of sex-steroids E.g. Oestradiol/Testosterone 

Development of secondary sexual characteristics

Attain capability to reproduce
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2
Q
  • What is gonadarche, thelarche, menarche, spermarche, adrenarche and pubarche?
A

Gonadarche - Activation of gonads by HPG axis.

Thelarche - Onset of breast development 

Menarche - Onset of first menstrual cycle 

Spermarche - Onset of spermatogenesis 

Adrenarche - Onset of adrenal androgen production 

Pubarche - Onset of pubic hair
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3
Q
  • What is the first sign of puberty in girls and boys respectively?
  • What is often used to see what the testicular volume should be at each stage of life?
A

Girls - Thelarche
Boys - Testicular volume

Prader- Orchidometer
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4
Q
  • Which hormones lead to the development of secondary sexual characteristics in boys and girls and what are the secondary sexual characteristics in boys and girls?
A

Girls

Oestradiol

Breast development, hair growth (pubic+axillary), sweat gland composition - skin oiliness/acne and changes to external genitalia

Boys

Testosterone

Deepening of voice, hair growth (Pubic then axillary+facial), sweat gland composition - acne/skin oiliness and changes to external genitalia
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5
Q
  • Which hormones are produced by the adrenal glands that increase in concentration with age?
  • What does gonadarche activate?
A

DHEAS/DHEA: Adrenal androgens

**HPG Axis** → Increase in LH and FSH
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6
Q
  • Outline the HPG-axis
A

Kisspeptin neurones associated with the hypothalamus regulate the pulsatile secretion of GnRH
From parvocellular hypothalamic neurones into the primary capillary plexus within median eminence
Enters the portal-hypophyseal pituitary circulation
GnRH stimulates the release of LH and FSH from gonadotrophs in anterior pituitary within the HPG.
These hormones stimulate the ovaries and testes to produce testosterone and oestrogen

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7
Q
  • How would you describe normal GnRH secretion?
  • What is mini-puberty?
  • What is precocious puberty and is it more common in girls or in boys?
A

Pulsatile secretion

The early/initial development and maturation of sex-organs

Early puberty (<8yrs)
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8
Q
  • What is the difference between primary and secondary amenorrhoea?
A

Primary - Having your first menstrual cycle later than 16 years > Regarded as abnormal

Secondary - Irregular periods/anovulatory for first 18 months. Periods start, but then stop for at least 3-6 months

(Essentially, primary is having late delayed menarche whereas the secondary is an adult not having menstrual cycles for at least 3-6 months)
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9
Q
  • What is the most common physiological cause of secondary amenorrhoea?
  • What is oligo-menorrhoea?
A

Pregnancy

Irregular or infrequent periods >35 day cycle OR 4-9 cycles in total per year.
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10
Q

Outline the menstrual cycle

A

Follicular phase: FSH levels rise leading to the growth of 2-3 follicles. Then E2 and inhibin are produced, which reduce FSH levels via a negative feedback loop and restrict the ‘FSH window’. Non-dominant follicles undergo atresia (die) due to lack of FSH.

Follicular phase (Pre-ovulatary phase): Dominant Graafian follicle emerges. E2 continues to increase due to switch to a positive feedback system by high E2 inducing LH surge causing ovulation. Induction of LH stimulates ovulation, secretion of mature secondary oocyte from the Graafian follicle → Remnant follicle = Corpus luteum.

Luteal phase: Corpus luteum development through LH secretion→ secretes progesterone to maintain the endometrium lining. Progesterone level test for mid-luteal to identify ovulation. Decreases negative feedback effect, subsequently increasing FSH levels. Oestradiol is also secreted.

Corpus luteum degrades due to absent HCG stimulation → Shedding of endometrium lining → Menstrual cycle restarts.

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11
Q
  • What happens in pregnancy that is different to a normal Menstrual cycle?
  • What does continuous non-pulsatile administration of GnRH cause?
A

Beta hCG secretion → Activates FSH and LH receptors → Continues to support the corpus luteum → Secretion of progesterone

Decrease LH and FSH secretion → Decreased oestradiol and testosterone
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12
Q
  • Outline GnRH pulsatility during the follicular and luteal phase of the Menstrual cycle.
A

During the follicular phase, GnRH pulsatility stimulates increased release of FSH for follicular development of Graafian follicle (Every 90-120 minutes)

Mid-cycle LH cycle due to positive feedback exertion of E2 → Increased pulsatility

Luteal phase: Negative feedback of progesterone therefore decreases pulsatile effect of GnRH
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13
Q
  • What is the difference between primary and secondary hypogonadism?
A

Primary - Gonads aren’t releasing their respective hormones hence Low E2/Testosterone and High FSH/LH (due to negative feedback loop in HPG axis)

Secondary - Low LH/FSH leading to low E2/testosterone

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14
Q
  • What can cause primary hypogonadism in men?
  • What is the commonest physiological cause of primary hypogonadism in women?
  • A rise in which hormone can cause secondary hypogonadism?
A

Men - Infection, trauma, cancer of testes

Menopause

Prolactin (prolactinoma formation or drugs used for psychiatric treatment)
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15
Q
  • What are the symptoms of menopause due to a lack of oestradiol?
A

Skin dryness/Hair thinning

Hot flushes/Sweating/sleep disturbance

Mood disturbance

Osteoporosis

Sexual dysfunction

Weight gain

Amenorrhoea

Cessation of fertility

Climacteric - Irregular periods in years close to Menopause
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16
Q
  • How can you treat menopause?
A

Oestrogen replacement - HRT (hormone replacement therapy). Oestrogen stimulates the endometrium to grow

Add progesterone (if Endometrium is already intact to prevent Endometrial hyperplasia which can predispose to cancer)
17
Q
  • Which cells secrete Anti-Mullerian Hormone (AMH) in the ovaries and when do AMH levels peak during life?
  • What can AMH levels be a good marker for?
A

Granulosa cells
Peaks in early adult life (Very low at menopause)

Ovarian reserve

18
Q
  • How can you diagnose Premature Ovarian Insufficiency (Early Menopause)?
  • What are the causes of Premature Ovarian Insufficiency?
A

High FSH > 25iU/L (has to be on 2 different occasions at least 4 weeks apart)

Autoimmune

Genetic e.g.Fragile X syndrome/ Turner’s Syndrome

Cancer therapy Radio/chemotherapy in the past
19
Q
  • Roughly how much testosterone is ‘free’?

- What is most testosterone bound to, making it unavailable?

A

2%
(38% Albumin-bound testosterone weakly → Can become available)

Sex-hormone binding globulin (SHBG) - 60%
(Albumin weakly binds Testosterone → Means that testosterone is still bioavailable ~38%

20
Q
  • In ‘Late Onset Hyogonadism’ in men, what is there a significant increase in?
A

Sex-hormone binding globulin (SHBG) is increased (free testosterone is reduced hence total testosterone is unchanged)

21
Q
  • What are the symptoms of testosterone deficiency?
A

Sexual dysfunction - Reduced libido
Erectile dysfunctions > Loss of early morning erections
Hair growth - Frequency of shaving
Energy levels - General wellbeing, Fatigue
Mood disturbance
Body composition changes - Increased fat + reduced muscle mass
Gynaecomastia (breast enlargement in men)
Spermatogenesis - High levels of intertesticular testosterone needed
Bone health - Testosterone sometimes converted to oestrogen when present; lack thereof can lead to osteoporosis

22
Q
  • What enzyme converts testosterone to oestrogen and where can it be found? Which oestrogen does this enzyme convert testosterone and androstenedione into?
A

Aromatase; adipose tissue, adrenal glands, ovaries (granulosa cells), testes (sertoli cells), brain, bone and skin

Testosterone → 17 Beta-oestradiol

Androstenedione → Oestrone
23
Q
  • What factors cause increased activity of aromatase?
A

Age

Obesity

Insulin

Gonadotrophins

Alcohol
24
Q
  • Where can you find the enzyme 5-alpha-reductase?
A

Testes (seminal vesicle, epididymis)

Prostate 

Skin > Scalp 

Liver
25
Q
  • What is the difference between testosterone and dihydrotestosterone (DHT)?
A

Dihydrotestosterone is a more potent ligand for the androgen receptor

DHT has a role in pubic and facial hair growth, prostate and male pattern baldness

However, it is testosterone which regulates libido, erectile function and fertility
26
Q
  • What can aromatase inhibitors such as anostrazole be used to treat?
  • What can 5-alpha-reductase inhibitors such as finasteride be used to treat?
A

Breast cancer

Prostate cancer
27
Q

what does 5-alpha-reductase do?

A

Convert testosterone to dihydrotestosterone