Pituitary Physiology Flashcards
What are the pituitary and peripheral steroid hormones
ACTH and cortisol
What are the pituitary and peripheral thyroid hormones
TSH and thyroxine
What are the pituitary and peripheral sex hormones
LH/FSH and testosterone or oestradiol
What are the pituitary and peripheral growth hormones
GH and IGF-1
What are the pituitary and peripheral steroid hormones
Only pituitary hormone which is prolactin
What can be compressed if a pituitary tumour grows extensively
Cranial nerves
Optic chiasma
Internal carotid arteries
Sphenoid sinus
By what route do we usually remove a pituitary tumour
Though the sphenoid sinus
If we think the pituitary is secreting too much hormone, what test do we do
One to try and suppress the hormone
If we think the pituitary is secreting too little hormone, what test do we do
One to try and stimulate the hormone
How do we know if there is a problem in a dynamic test
There will be no response to either suppression or stimulation of the hormone
How can we do a dynamic pituitary test
Insulin stress test
Describe the normal result of a stress test to insulin
The blood glucose will decrease dramatically for the first half hour before insulin, growth hormone and cortisol will all increase to compensate and react to the hypoglycaemic environment
What patients should not be subjected to an insulin stress test
Those with epilepsy or ischaemic heart disease
What should be used instead of an insulin stress test in patients with epilepsy or ischaemic heart disease
prolonged Glucagon test
How can we test ADH
Deprive the patient of water and make them dehydrated
How can we diagnose Diabetes Insipidus
If there is an abnormal Urine/serum Osmolality is less than 2, 8 hours after a water deprivation test
What is the name of a pituitary tumour
Microadenoma
What is the name of pituitary tumour >1cm
Macroadenoma
What are the chances of a non-functioning pituitary being benign
90%
Do non-funcitoning pituitary adenomas produce hormones
No
Why are non functioning adenomas a problem
They can wipe out the cells of the pituitary that do produce hormones
What can a non functioning pituitary adenoma cause
Hypoadrenalism
Hypothyroidism
Hypogonadism
Growth hormone deficiency
What is bitemporal hemianopia
When the temporal visual field is obliterated due to a pituitary tumour
What are some physiological causes of raised prolactin
Breast feeding
Pregnancy
Stress
Sleep
What drugs can cause an increase of prolactin
Dopamine antagonists
Antipsychotics
Antidepressants
What is elevated in an underachieve thyroid
TRH and TSH
If there is elevated, TRH what can occur
Increased stimulation of prolactin
What are some examples of cases where there will be an increase in prolactin
Hypothyroidism
Road accidents or iatrogenic causes of stalk lesion
What are some of the clinical signs in a female of increased prolactin
Galactorrhoea
Menstrual irregularity
Ammenorrhoea
Infertility
What are some of the clinic signs in a male of increased prolactin
Impotence
Visual field abnormalities
Headache
Anterior pituitary malfunction
Males will present earlier than females with increased prolactin
No - they always present late
What are the main investigations for prolactinoma
Prolactin concentrations
MRI pituitary
Visual fields
Pituitary function tests
What should also be checked when checking for prolactin in the serum
Thyroid function test
What are the 3 main dopamine agonists to treat prolactinoma
Bromocriptine
Quinagolide
Cabergoline
What do dopamine agonists do
reduce prolactin levels and can make tumours shrink
What dopamine agonist is usually used in prolactinoma and why
Cabergoline (Dostinex)
it has the least side effects
What is the cause of acromegaly
Growth hormone excess
What are some features of acromegaly
thickened and soft skin, large jaw, sweaty, large hands
What are some side effects of acromegaly
Hypertension, cardiac failure Headaches Snoring/ sleep apnoea Diabetes mellitus Early CV death colonic polyps and colon cancer
How can we make a diagnosis of acromegaly
GTT suppression test
- GH will have no change after glucose
What other tests should be done for suspected acromegaly
Visual field
CT or MRI pituitary scan
Pituitary function tests
What are the treatment options for acromegaly
Pituitary surgery
External radiotherapy to pituitary fossa
Rest GTT
What are some side effects of somatostatin analogues
Local stinging
Short term include flatulence, diarrhoea and abdominal pains
Long term include gastritis and gallstones
What are the 2 more commonly used somatostatin analogues in acromegaly
Sandostatin LAR and Lanreotide autogel
Why is Pegvisomant hardly ever used
It is extremely expensive and most patients will respond to other treatment
What should be involved in an acromegaly follow up
Other pituitary hormones should be checked
Cancer surveillance
Cardiovascular risk factors
Sleep apnoea
Dopamine inhibits release of prolactin. True or false
True
What does ACTH do to the adrenal glands
Stimulates them to produce cortisol
What is the first line treatment for prolactinoma
Dopamine agonists
What is the most common cause of an acromegalic headache
Vascular effects such as increased blood flow
