Ovulation Disorders and Male Hypogonadism Flashcards
Sequence of events in the hypothalamic pituitary gonadal axis?
GnRH released from the hypothalamus
This stimulates the anterior pituitary to produce LH and FSH, which have their own effects on target tissues
-ve or +ve feedback can occur, from steroid and peptide hormones (like oestrogen) at the gonads, affecting:
• GnRH release from the hypothalamus
• LH and FSH release from the anterior pituitary
Functions of oestrogenes?
Class of steroid hormones that control development and maintenance of female sexual characteristics
Where does glandular oestrogen synthesis occur?
Occurs in the granulosa and theca cells of the ovaries, as well as the corpus luteum
What happens when granulosa cells are stimulated by LH?
Produce pregnenolone
What happens to pregnenolone?
- Diffuses out of granulosa cells into adjacent theca cells which express enzymes (17,20-lyase and 17β-HSD)
- Enzymes mediate pregnenolone conversion to androstenedione (via DHEA)
- Most andosteedione returns to the granulosa cells and is converted to oestrone by aromatase
- Aromatase is then converted to oestradiol (by 17β-HSD)
How is expression of aromatase and 17β-HSD controlled?
By FSH stimulation
How does extraglandular synthesis of oestrogen occur?
Aromatase is expressed in non-gonadal sites and facilitates peripheral aromatisation of androgens to estrone, e.g: fat and bone
How is progesterone synthesised?
Synthesised from pregnenolone (by 3β-HSD in the corpus luteum) by the:
• Placenta during pregnancy
• Adrenal glands, as a step in androgen and mineralocorticoid synthesis
Mediation of progesterone actions?
Intracellular progesterone receptor, no. of which increase in the presence of oestrogen
Main productions of hormone synthesis at different phases in the menstrual cycle?
During follicular maturation - oestradiol
Luteal phase - progesterone (following ovulation)
Time period for ovulation and menstrual cycle?
Menstrual cycle begins on day 1 of the period
There are 2 phases following menses:
• Follicular phase - in the weeks leading up to ovulation
• Luteal phase - in the weeks following ovulation (progesterone peaks)
During ovulation, LH, FSH and oestrogen peak in levels
Definition of oligomenorrhea?
Reduction in frequency of periods to <9 per year
Definitions of primary and secondary amenorrhea?
Primary - failure of menarche by the age of 16 years (likely a congenital/genetic condition)
Secondary - cessation of periods for >6 months in an individual who has previously menstruated (likely an acquired cause)
Physiological causes of amenorrhoea?
- Pregnancy
2. Post-menopausal (usually >40 years of age)
Causes of primary amenorrhea?
Congenital problems, e.g:
• Turner’s syndrome
• Kallman’s syndrome
Causes of secondary amenorrhea?
Ovarian problem, e.g:
• PCOS
• Premature ovarian failure (can cause early menopause)
Uterine problem, e.g:
• Uterine adhesions
Hypothalamic dysfunction, due to e.g: • Stress • Weight loss • Exercise • Infiltrative causes
Pituitary, e.g:
• High PRL
• Hypopituitarism
Features of to check for in an amenorrhea history?
Symptoms of oestrogen deficiency:
• Flushing
• Libido
• Dyspareunia (painful intercourse)
Hypothalamic problem indications, e.g: weight loss, stress, exercise
Features of PCOS/androgen excess:
• Hirsutism
• Acne
Features of Kallman’s:
• Anosmia (loss of sense of smell)
Symptoms of hypopituitarism/pituitary tumour:
• Galactorrhea
Drugs assoc. with hyperprolactinaemia
Features to check for on examination of a patient presenting with amenorrhea?
Body habitus (for Turner’s)
Visual fields and anosmia
Breast development
Hirsutism, acne (androgen excess)
Ix that should always be done in a patient with oligo/amenorrhea?
LH, FSH and oestradiol
TFTs
Prolactin
Additional Ix for amenorrhea?
Ovarian USS +/- endometrial thickness (if it is thin, this indicates decreased oestrogen)
Testosterone (if there is hirsutism)
Pituitary function tests +MRI pituitary (if hypothalamic pituitary problems suspected)
Karyotype (if primary amenorrhea or features of Turner’s syndrome)
How is female hypogonadism detected?
Low levels of oestrogen
What is primary hypogonadism?
Problem with ovaries; there is a high LH/FSH (hypergonadotrophic hypogonadism)
Example is premature ovarian failure
What is secondary hypogonadism?
Problem with hypothalamus or pituitary; there is a low LH/FSH (hypogonadotrophic hypogonadism) and a low oestradiol
E.g: in high PRL, hypopituitarism
How to interpret LH/FSH measurements for a presentation of amenorrhea?
If high LH/FSH (esp. FSH):
• Primary ovarian problem
Low/inappropriately normal LH/FSH:
• Primary pituitary problem
• Hypothalamic problem
Presentation of premature ovarian failure (POF)?
Loss of ovarian function occurring <40 years of age with:
• Amenorrhea
• Oestrogen deficiency
• Elevated gonadotrophins
Diagnosis of premature ovarian failure?
FSH >30 on 2 separate occasions that are >1 months apart
Causes of premature ovarian failure?
Chromosomal abnormalities, e.g:
• Turner’s syndrome
• Fragile X
Gene mutations, e.g:
• In the FSH/LH receptor
Autoimmune disease, e.g: can be assoc. with:
• Addison’s disease
• Thyroid disease
• APS1/2
Iatrogenic, with radio/chemotherapy
Causes of secondary hypogonadism?
Hypothalamic problem:
• Functional hypothalamic disorders
• Kallman’s syndrome
• Idiopathic hypogonadotrophic hypogonadism (IHH)
Pituitary problems
Miscellaneous:
• Prader-Willi
• Haemochromatosis
Types of functional hypothalamic amenorrhea?
3 main types:
• Weight change related
• Stress related
• Exercise related
This can occur, e.g: in athletes, anorexia nervosa
Other causes of functional hypothalamic amenorrhea?
Anabolic steroids, recreational drugs
Iatrogenic, e.g: surgery/radiotherapy
Systemic illness
Infiltrative disorders, e.g: sarcoidosis
Head trauma