hypopituitarism Flashcards
What hormones does anterior pituitary produce?
ACTH (cortisol), LH/FSH (for oestrogen/testosterone), TSH (for T3/4), prolactin, GH
What is origin of anterior pituitary? What does it require and how does that work?
Glandular origin. Requires hypothalamus to release inhibitory/releasing factors that travel via portal circulation to anterior pituitary stimulating it to produce the hormones.
What is primary failure or secondary failure. What is low / high in each
Primary is failure of the organ itself, secondary is failure of other organs. In primary hypothyroidism for example, T3/4 is low, but TSH is high. In secondary hypo, all 3 are low.
What is the best way to look at the pituitary?
MRI
In rare congenital causes of hypopituitarism what is the usual cause? What are they usually deficient in? what is seen on MRI?
Mutations in transcription factors of the anterior pituitary development eg. PROP1. usually deficient in GH and 1 more hormone. On MRI see hypoplastic (underdeveloped) pituitary gland
What is it called when both pituitaries are damaged? What can cause this?
Panhypopituitarism. Inflammation (hypophysitis)
Why can radiation cause hypopituitarism? Which hormones are usually affected? How long does the risk persist after radiotherapy?
Radiation can affect the pituitary gland or hypothalamus with direct or indirect radiation. Gonadotrophin hormones are usually affected first (sensitive). Then GH. Can also cause high prolactin by affecting hypothalamic dopamine. Risk persists for 10 years after.
What is sheehan’s syndrome and what causes it? What are the symptoms associated with it?
During pregnancy there is lactotroph hyperplasia (anterior pituitary grows). Haemorrhage during pregnancy causes hypotension which causes infarction (lack of blood flow to anterior pituitary) and the 5 hormones stop being produced. Symptoms include inability to breastfeed (prolactin), fatigues, lethargy, anorexia, weight loss, no periods after delivery
What is pituitary apoplexy and what causes it? What can precipitate it? What can be the consequences apart from hypopituitarism?
Pituitary apoplexy is usually caused by intra-pituitary haemorrhage and rarely infarction. Usually due to bleeding into existing pituitary tumour. It can be precipitated by blood thinners or anticoagulants. Bleeding can push onto optic chiasm causing bitemporal hemianopia. Can push on cavernous sinus causing ptosis/diplopia. Get sudden very dramatic headache.
What are the biochemical features of each anterior pituitary hormone?
Cortisol is diurnal, LH/FSH cyclical in women, GH/ACTH are pulsatile, T4 (thyroxin) has 6-day half life so may be high and then 6 days later may be low.
What is dynamic pituitary function and how is it used to diagnose hypopituitarism?
series of hormone measurements over series of time points (insert cannula in for lots of tests). Induce hypoglycaemia using insulin in order to see rise in GH/ACTH (should rise to correct hyperglycaemia). Inject with TRH to see rise in TSH. Inject with GnRH injection to see rise in LH/FSH.
What else can be used for diagnosis of hypopituitarism?
Radiological (MRI) can see apoplexy /infarction.
How many of the hormones in hypopituitarism can be treated?
all except prolactin deficiency
How is GH deficiency confirmed? What is the management? How Is it monitored?
Confirmed with dynamic pituitary test. Given quality of life questionnaire and growth hormone daily injection. Monitored with quality of life assessment and IGF1 levels
How is TSH deficiency treated? What is the goal?
levothyroxine. Goal is ft4 above mid-normal range.
