Lactation, galactorrhoea and prolactinomas Flashcards
Which hormones are involved in breast development during puberty?
oestrogen, progesterone.
GH (via IGF-I) increases alveolar buds and lobules.
Which hormones are involved in milk production?
secretory initiation: progesterone, occurs during pregnancy, colostrum.
secretory activation: decreased oestrogen and progesterone, increased prolactin (cortisol, insulin), copious milk production after delivery.
What are the mechanical factors and hormones involved in lactation?
positive feedback loops.
regular removal of milk, nipple stimulation.
prolactin (anterior pituitary) and oxytocin (posterior pituitary).
Which hormones stimulate or inhibit prolactin?
hypothalamus secretes dopamine which inhibits.
stimulated by 5HT (serotonin), TRH, oxytocin.
Why does amenorrhoea occur during lactation?
high prolactin levels decrease GnRH, LH and FSH and pulsatility, oestrogen and testosterone.
How is the production of oxytocin mechanically regulated?
Afferent signal from receptors in the nipple when the infant suckles ascend to hypothalamus.
stimulated by:
uterine myometrial contraction at birth
smooth muscle activation in breast - ‘myoepithelial contraction’
milk let-down
What is the presentation of hyperprolactinaemia in women?
oligo / amenorrhoea - increased risk osteoporosis
galactorrhoea
subfertility
(may not have all these symptoms. may present after stopping contraceptive pill -
coincidental)
What is the presentation of hyperprolactinaemia in men?
Erectile dysfunction decreased libido visual symptoms headaches hypopituitarism (present later) galactorrhoea / gynaecomastia - rare
What are the causes of hyperprolactinaemia?
Physiological - pregnancy,
lactation
Hypothalamic-pituitary disease - micro / macroPRLoma,
non-functioning adenoma
Drugs
Stress
Other - PCOS, hypothyroidism (increased TRH), renal failure, cirrhosis
How can a non-functioning adenoma on the pituitary affect prolactin levels?
doesn’t directly stimulate the production of prolactin, but stops the inhibition of dopamine
Which drugs increase the levels of prolactin and what is their mechanism?
Antidepressants and antipsychotics. drugs used for nausea and vertigo - phenothiazines,
metoclopramide,
domperidone. Others.
Inhibition of secretion / action of dopamine - DA antagonists,
DA receptor blockers.
Stimulation of central serotonin (5HT) pathways - 5HT re-uptake inhibitors.
What investigations should be carried out when a patient has high prolactin levels?
Pregnancy test Renal function - U&E, creatinine Liver function tests Thyroid function Prolactin (repeat) LH, FSH Testosterone (men) MRI pituitary - micro < 1 cm diameter, macro > 1 cm diameter. Macroadenoma - visual fields, rest of anterior pituitary function tests.
What are the aims of treatment for hyperprolactinaemia?
Restore fertility
Stop galactorrhoea - also stop nipple stimulation
Restore regular menstrual periods / libido - oestrogen / testosterone needed for bone protection, can use exogenous oestrogen / testosterone (contraceptive pill / HRT / testosterone)
Shrink tumour (macroadenoma) - recovery of anterior pituitary function, restore vision.
How is PRLoma managed?
Medical: dopaminergic drugs - cabergoline, (bromocriptine),
preserve pituitary function,
rare side-effects.
How are microPRLomas managed?
COCP / HRT if fertility not required
Can discontinue treatment in pregnancy
May involute post-partum
Can trial withdrawal of treatment after ~ 2 years (may not recur).
