Clinical (Week 5 - Calcium and Reproduction) Flashcards
Where are oestrogens synthesised?
Ovaries:
- Granulosa
- Theca cells
Corpus luteum
What does LH stimulate the granulosa cells to produce?
Pregnenolone
What diffuses from the granulosa cells to the adjacent theca cells and what does this cause?
Pregnenolone
Causes theca cells to express:
- 17,20-lyase (also known as 17α-Hydroxylase)
- 3β-HSD
What happens when the theca cells express the enzymes in response to pregnenolone?
Pregnenolone is converted to DHEA:
- By 17α-hydroxylase
DHEA is converted to androstenedione:
- By 3β-HSD
What other function does 3β-HSD have?
Converts pregnenolone to progesterone
What are the three types of naturally occurring oestrogen in the body?
Oestrone (E1)
Oestradiol (E2)
Oestriol (E3)
What happens to most androstenedione?
Returns to granulosa cells:
- Converted to oestrone (E1) by aromatase
What function does 17β-HSD have?
Converts oestrone (E1) to Oestradiol (E2) (Also converts Androstenedione to testosterone)
What enzymes does FSH increase the expression of?
Aromatase
17β-HSD
(Both from the granulosa cells)
Where else can oestrogens be synthesised?
Aromatase is expressed in fat and bone:
- Peripheral production of Oestrone (E1)
Where is progesterone synthesised and by what enzyme?
Made from pregnenolone by 3β-HSD in:
- Corpus luteum - Placenta (during pregnancy) - Adrenal glands
Why is progesterone made in the adrenal glands?
Step in androgen and mineralocorticoid production
During the following stages, what products are mainly made from pregnenolone:
- Follicular maturation
- Following ovulation (Luteal phase)
Follicular maturation:
- Oestradiol (E2)
Luteal phase:
- Progesterone
What is oligomenorrhoea?
Reduced period frequency to less than 9/year
OR
Having a menstrual cycle > 35 days
What is primary amenorrhoea?
Failure of menarche by 16 years of age
What is secondary amenorrhoea?
Cessation of periods for >6 months:
- In a woman who previously menstruated
What are the two physiological causes of amenorrhoea?
Post-menopausal state
Pregnancy
What can cause primary amenorrhoea?
Turner’s Syndrome (45, XO)
Kallman’s Syndrome
A 19 year old woman presents concerned that she hasn’t started menstruating. She has also noted that her breasts have hardly developed. On examination you notice she has no sense of smell (anosmia). You decide to test her pituitary hormones and discover a lack of LH and FSH.
Kallman’s Syndrome
What ovarian problems may cause secondary amenorrhoea?
PCOS
Premature ovarian failure
Which of these does not cause hypothalamic dysfunction and therefore does not cause secondary amenorrhoea:
- Weight loss
- Over exercise
- Poor sleep
- Stress
- Infiltrative disease
Poor sleep
What pituitary problems can result in amenorrhoea?
Increased PRL
Hypopituitarism
Flushing, reduced libido and dyspareunia are signs of what?
Oestrogen deficiency
What is dysparenuia?
Difficult or painful sex
What are features of PCOS?
Acne
Hirsutism
What blood tests should be done in oligo/amenorrhoea?
LH/FSH/Oestradiol
What additional investigations can be done if the following are suspected:
- Hirsutism
- Hypothalamic/Pituitary problem
- Primary amenorrhoea or Turner’s
- PCOS
Hirsutism: - Testosterone Hypothalamic/Pituitary problem: - Pituitary function tests - MRI pituitary Primary amenorrhoea or Turner's: - Karyotype PCOS: - USS
What is primary hypogonadism and what can cause it?
An ovarian problem: - Increased LH/FSH - Reduced response to gonadotropins > Hypergonadotropic Hypogonadism - eg. Premature Ovarian Failure
What is secondary hypogonadism and what can cause it?
Problem with hypothalamus and/or pituitary:
- Reduced/Inappropriately normal LH/FSH
> Hypogonadotropic Hypogonadism
- Can be due to
> High PRL
> Hypopituitarism
How many times must FSH be high to suggest a diagnosis of premature ovarian failure? What must it be greater than
FSH >30:
- 2 separate occasions -> Greater than 1 month apart
What age are patient’s suffering from premature ovarian failure?
Women younger than 40
What chromosomal abnormalities can cause premature ovarian failure?
Turner’s
Fragile X
What gene mutations can cause premature ovarian failure?
LH/FSH receptor mutations
What autoimmune conditions are associated with premature ovarian failure?
Addison’s
Thyroid
APS1/1 (Autoimmune Polyendocrine Syndrome)
What iatrogenic causes are there of premature ovarian failure?
Radiotherapy
Chemotherapy
What are some hypothalamic causes of secondary hypogonadism?
Functional disorders
Kallman’s Syndrome
Idiopathic Hypogonadotropic Hypogonadism (IHH)
What are some other causes of secondary hypogonadism?
Prader-Willi (Chromosome 15q11-13 mutations)
Haemochromatosis
What are the most common causes of functional hypothalamic amenorrhoea?
Weight change
Stress
Exercise
Which of the following is not a sign/symptome of IHH:
- Absent/Delayed sexual development
- Reduced gonadotropins
- Increased sex steroids
- Absence of hypothalamic-pituitary axis defects
Increased sex steroids:
- They are reduced in IHH
What underlies IHH?
Inability to activate pulsatile GnRH secretion in puberty
What genetic defects may cause IHH?
GnRH neuron migration
GnRH secretion
GnRH action
What role does Kisspeptin have and how can this be linked to IHH?
Functions: - Potent stimulator of GnRH release - Gatekeeper of puberty - Regulates male and female fertility - Influences ovulation and menstruation Mutations in the KISS1R receptor: - Prevents Kisspeptin binding > Reduces GnRH release
What would be seen on MRI of a patient with Kallman’s syndrome and how does this reflect on one of the symptoms?
Normal pituitary gland
BUT
No olfactory bulb -> Hypo-/Anosmia
What is the male:female ratio for Kallman’s Syndrome?
4:1
What can cause pituitary dysfunction?
Non-functioning pituitary macroadenoma:
- Pressure -> Hypopituitarism
Empty sella
Infarction (Apoplexy)
What can cause hyperprolactinaemia?
Prolactinomas Pituitary pathology Drugs: - Antipsychotics - Dopamine antagonists Hypothyroidism Macroprolactin: - False hyperprolactinaemia
What are the Rotterdam criteria for PCOS?
2 of: - Menstrual irregularity - Hyperandrogenism > Hirsutism > Increased free testosterone - Polycystic ovaries
What are some congenital causes of poor ovarian development?
Absence of uterus Vaginal atresia Turner's Testicular feminisation CAH
What causes hirsutism?
Excess androgen at hair follicle:
- Due to excess circulating androgen - Peripheral conversion to testosterone at follicle
In what populations is familial hirtuism common?
Mediterranean
What are the features of these causes of hirsutism:
- PCOS
- Familial
- Idiopathic
- Non-classical CAH
Long histories
Serum testosterone
What can cause a short history of hirsutism with signs of virilisation?
Adrenal/Ovarian tumour
What testosterone levels are seen in androgen-secreting tumours? What size do these tumours tend to be on MRI
> 5nmol/L
>1cm
How can PCOS be treated?
Oral contraceptive: - Regulates cycle - Reduces ovarian androgens Anti-androgens: - Cyproterone acetate - Efflornithine cream Cosmesis: - Electrolysis - Laser phototherapy
How can late onset CAH be treated?
Low does glucocorticoid (reduces ACTH drive)
What is the incidence of Turner Syndrome?
1 in 2000 women
How many spontaneous abortions is Turner Syndrome responsible for?
15%
What are some defining clinical features of Turner Syndrome?
Short stature Webbed neck Wide spaced nipples Cubitus valgus: - Forearm angled away from body
What are some CVS effects of Turner Syndrome?
Aortic coarctation
Bicuspid aortic valve
Hypoplastic left heart
What GI problems are patients with Turner Syndrome more likely to have?
Crohn’s
UC
If a patient has no chromosomal abnormalities, yet absent ovaries, what is this due to?
XX Gonadal Dysgenesis
A patient’s karyotype is 46 XY, yet they are phenotypically female.
Testicular feminisation:
- Androgen Insensitivity Syndrome - Pseudohermaphrodites
What biochemistry is seen in primary male hypogonadism?
Reduced testosterone
Increased LH/FSH
What biochemistry is seen in secondary male hypogonadism?
Reduced testosterone
Reduced/Inappropriately normal LH/FSH
What are some congenital causes of primary male hypogonadism?
Klinefelter’s
LH/FSH receptor mutations
What are some acquired causes of primary male hypogonadism?
Testicular trauma
Haemochromatosis
What are some congenital causes of secondary male hypogonadism?
Kallman’s
Prader-Willi
What are some acquired causes of secondary male hypogonadism?
Hyperprolactinaemia
Pituitary damage
What examination signs are relevant in diagnosing male hypogonadism?
Staging of puberty
Testicular volume
Visual fields
What level of total testosterone may suggest male hypogonadism?
If testosterone is low, what must be done next?
Repeat total testosterone
OR
If SHBG variation suspected:
- Measure free testosterone
What free testosterone level suggest male hypogonadism?