T1 L15 Lactation and prolactinomas Flashcards
What causes breast development during puberty?
Oestrogen
Progesterone
Growth hormone via IGF-1 leads to increased alveolar buds and lobules
What causes breast development during pregnancy?
Oestrogen
Progesterone
hCG, prolactin
Alveolar development
What initiates the secretion of milk production?
Progesterone
Occurs during pregnancy leading to production of colostrum
What activates the secretion of milk production?
Decreased progesterone and oestrogen
Increased prolactin
What is the composition of milk?
Sugar Milk fats Proteins Minerals Growth factors Cellular components
What is galactopoiesis?
Maintenance of lactation once lactation has been established
Describe lactation amenorrhoea
Contraceptive efficacy depends on frequency and duration of breast feeding
Becomes less effective the longer since the birth
Where is prolactin produced?
By lactotroph cells in anterior pituitary
What inhibits prolactin release?
Dopamine
What stimulates prolactin release?
5HT (serotonin)
TRH
Oxytocin
What does increased prolactin lead to?
Decreased GnRH
Decreased LH and FSH and decreased pulsatility
Decreased oestrogen / testosterone
Where is oxytocin synthesised?
In the hypothalamic magnocellular neurons
- supraoptic nucleus
- paraventricular nucleus
Where is oxytocin released from?
Posterior pituitary
-distal axon terminals of hypothalamic magnocellular neurons
What are the roles of oxytocin?
Cause uterine myometrial contraction at birth
Cause smooth muscle activation in breast (myoepithelial contraction)
Causes milk let down
May have a role in maternal behaviour
How do other mammals know that they’re pregnant?
Brain responds to hormonal changes associated with ovulation, mating, implantation and pregnancy
Via prolactin and placental lactogens
Describe how hyperprolactinaemia presents
Women:
- oligomenorrhoea
- galactorrhoea
- subfertility
Men
- erectile dysfunction
- decrease in libido
Visual symptoms
Headaches
Hypopituitarism
What are the general causes of hyperprolactinaemia?
Physiological
Hypothalamic - pituitary disease
Drugs
Stress
What are some other causes of hyperprolactinaemia?
PCOS
Hypothyroidism
Renal failure or cirrhosis
What are some physiological causes of hyperprolactinaemia?
Pregnancy
Lactation
What are some hypothalamic-pituitary cases of hyperprolactinaemia?
Micro / macro-prolactinoma
Non-functioning adenoma
What drugs can cause hyperprolactinaemia?
Antidepressants and antipsychotics
Dopamine antagonists used for nausea and vertigo such as phenothiazines, metoclopramide and domperidones
How do drugs cause hyperprolactinaemia?
Inhibit secretion / action of dopamine
- dopamine antagonists
- dopamine receptor blockers
Stimulation of central serotonin pathways
-5HT re-uptake inhibitors
What investigations should be done when suspecting hyperprolactinaemia?
Pregnancy test Renal function Liver function tests Thyroid function Prolactin LH and FSH Testosterone MRI of pituitary
What additional tests could be done when suspecting a macroadenoma?
Visual fields
Rest of anterior pituitary function tests
What is the management aims for hyperprolactinaemia?
Restore fertility
Stop galactorrhea
Restore menstrual periods / libido
Shrink tumour
What is the medical management for prolactinomas?
Dopaminergic drugs such as cabergoline or bromocriptine
What are the side effects of the drugs given for prolactinomas?
Fibrotic reactions -pulmonary -pericardial -retroperitoneal Psychiatric disturbance
Describe the treatment for micro-prolactinomas
Can take COCP / HRT if fertility is required
Can discontinue treatment in pregnancy
Can trial withdrawal of treatment after 2 years
Describe a non-functioning pituitary adenoma
Compression of pituitary stalk
- disconnection hyper-prolactinaemia
- may also occur with hypothalamic masses
