Physiology of menstruation and menstrual abnormalities

Question 1

What are the typical ages of menarche?

Answer 1

11-15

Question 2

What is menstruation?

Answer 2

Cyclical changes during the reproductive years
Monthly bleeding induced by hormonal changes

Question 3

What is the length of the cycle?

Answer 3

day 1 of one period to day 1 of next period

Question 4

Explain the hypothalamo-pituitary-ovarian axis

Answer 4

Hypothalamus releases GnRH to anterior pituitary

Anterior pituitary stimulated to release FSH and LH

This stimulates the ovary to release oestrogen and progesterone to the uterus

Question 5

Explain the effects of oestrogen and progesterone released during HPO axis

Answer 5

Oestrogen levels reduced the effect on the anterior pituitary initially. Once the oestrogen is at a high level, this has a positive effect on the anterior pituitary, leading to LH SURGE

Progesterone suppresses both FSH and LH

Question 6

What is the follicular phase of the menstrual cycle?

Answer 6

Rise in FSH stimulates follicle development
Follicle secretes oestrogen leading to suppression of FSH secretion
Endometrium proliferates

Question 7

What is ovulation phase of menstrual cycle?

Answer 7

Lasts 36-48hrs

At midcycle, negative feedback from oestrogen, changes to positive feedback leading to LH surge - leads to release of the egg from the dominant follicle (36hrs after surge)

Question 8

What is the luteal or secretory phase of menstrual cycle?

Answer 8

14 days
Rise in progesterone levels from the corpus luteum, peak levels 7 days after ovulation
Secretory changes in the endometrium

Question 9

What is prolactin?

Answer 9

Hormone causing lactation
High levels of prolactin inhibit ovulation (inhibit FSH and LH)

Question 10

What is anti-mullerian hormone?

Answer 10

a substance produced by granulosa cells in ovarian follicles

Question 11

When is anti-mullarian hormone first made?

Answer 11

first made in primary follicles that advance from the primordial follicle stage

Question 12

When is AMH production highest? When does it stop?

Answer 12

preantral and small antral stages of development - production decreases and stops as follicles grow

Question 13

What is primary amenorrhea?

Answer 13

No periods till 16yrs if secondary characters present

OR

No periods until 14yrs and absence of secondary sexual characteristics

Question 14

What is secondary amenorrhea?

Answer 14

Absence of periods for 6 months, after onset of menstrual cycles

Question 15

What is oligomenorrhea?

Answer 15

Cycles > 6 weeks, < 6 months

Question 16

What are physiological causes of amenorrhea?

Answer 16

Pregnancy
Lactation

Question 17

What are drug causes of amenorrhea?

Answer 17

Contraceptives
Steroids

Question 18

What are hypothalamic causes of amenorrhea?

Answer 18

Exercise
Anorexia Nervosa
Kallmann syndrome
Tumours

Question 19

What are pituitary causes of amenorrhea?

Answer 19

Pituitary adenoma e.g. prolactinoma
Sheehan’s syndrome
Surgery

Question 20

What are ovary causes of amenorrhea?

Answer 20

PCOS
Premature ovarian failure/resistant ovary syndrome
Ovarian dysgenesis e.g. Turner syndrome

Question 21

What are outflow tract causes of amenorrhea?

Answer 21

Imperforate hymen/Transverse vaginal septum
Mullerian agenesis - Mayer/Rokitansky-Kuster-Hauser (MRKH) syndrome

Question 22

What are sex disorders causes of amenorrhea?

Answer 22

Androgen insensitivity syndorme
Swyer syndrome

Question 23

What is precocious puberty?

Answer 23

Appearance of 2ry sexual characteristics < 8 years in girls

Question 24

What are central types of precocious puberty?

Answer 24

Gonadotrophin dependent:
- HPA axis activated
- Idiopathic
- CNS tumours

Question 25

What are peripheral types of precocious puberty?

Answer 25

Gonadotrophin independent:
- Isosexual e.g. exogenous hormones, granulosa cell tumour, MacCune Albright syndrome
- Contra-sexual - CAH, Androgen secreting ovaraian tumours