L15 - lactation

Question 1

Describe milk production

Answer 1

Initiation of secretion of breast milk starts in pregnancy by progesterone and colostrum production
Then activation of secretion when prog and oestrogen levels drop, prolactin levels rise then after 2/3 after delivery you get more copious milk production

Question 2

milk composition

Answer 2

sugar - lactose
milk fats - TG, cholesterol, steroid hormones
Proteins - lactoferrin, secretory IgA lysozyme
Minerals - sodium, k, cl, ca, mg, phosphate
growth factors
cellular components esp in colostrum - macrophages, neutrophils, epithelial cells

Question 3

Regulating lactation

Answer 3

regular removal of milk
nipple stimulation

hormones - prolactin from the ant pit
oxytocin - from post pit

Question 4

what makes prolactin

Answer 4

made by lactotrophe cells

similar to GH

Question 5

What inhibits and stimulates prolactin ?

Answer 5

dopamine inhibits

serotonin, TRH, and oxytocin stimulates

Question 6

Lactational amenorrhoea

Answer 6

When women are lactating they dont get mentrual periods due to suppressed gonadal axis

Contraceptive efficacy depends on the frequency and duration of breast feeding
so periods stop when women are breast feeding

Mechanism for this is increased prolactin
reduced GnRH
reduced LH/FSH reduced pulsatility
reduced oestrogen and testosterone

Question 7

Where is oxytocin made?

Answer 7

Synthesised in hypothalamic magnicellular neurons
Supraoptic nucleus
Paraventricular nucleus THEN transmitted down and secreted from the posterior pituitary gland

Question 8

What are the roles of oxytocin?

Answer 8

at birth it oxytocin stimulates uterine myometrial contraction
smooth muscle activation in breast - myoepithelial contraction
milk let down

Afferent signal from receptor in the nipple when infant suckles ascends to the hypothalamus

Question 9

Hyperprolocatinaemia - presentation in women

Answer 9

oligo/amenorrhoea
galactorrhoea - milky nipple discharge
subfertility

Question 10

Hyperprolactinaemia presentation in men

Answer 10

erectile dysfunction
reduced libido
visual problems
headaches

men present later
galactorrhoea and gynaecomastia rare

Question 11

Causes of hyperprolactinaemia

Answer 11

physiological causes: 
pregnancy / lactation 
hypothalamic - pituitary disease - micro or macro PRLoma / nonfunctioning adenoma 
Drugs 
stress
other- POS, renal failure

Question 12

what drugs increase prolactin?

Answer 12

antidepressants and antipsychotics

drugs used for nausea / vertigo - phenothiazines / metoclopramide

Question 13

Hyperprolactinaemia investigations?

Answer 13

Pregnancy test
renal function U+E/creatinine 
Liver function tests 
TFT 
prolactin repeat 
LH/FSH 
testosterone in men 

MRI pituitary
to see if macro or micro adenoma

Macroadenoma - visual fields

Question 14

aims of treatment

Answer 14

restore fertility
stop galatorrhoea
restore regular menstrual periods and libido
shrink tumour - macroadenoma (recovery of ant pit function and restore vision)

Question 15

How to manage PRLoma?

Answer 15

medical - dopaminergic drugs - cabergoline
preserve pit function

For MICROPRLOMA -
can take COCP/HRT if fertility not required

Question 16

How would you manage a non-functioning pituitary adenoma ?

Answer 16

May need pituitary surgery due to compression of the pituitary stalk
and need to monitor MRI and visual fields scan
prolactin levels go down with dopaminergic drugs, but in case of NFA prolactin levels go down but tumour does not shrink like it would with a prolactinoma