S8 Pituitary Disorders Flashcards
(46 cards)
What is the clinical presentation of pituitary tumours?
- visual loss
- headache
- hypo-/hyper-secretion (abnormality in pituitary function)
Why do you get visual field loss when a pituitary tumour grows upwards/superiorly?
It applies pressure on the optic chiasm
Why do you get double vision/pain when a pituitary tumour grows sideways/laterally?
Applies pressure to the nerve that controls eye movements and pain
A pituitary tumour can inhibit the function of the hypothalamic control on the pituitary gland, what does it affect? What is this called?
- no positive control of GH, LH/FSH, TSH or ACTH
- no negative control of prolactin (so prolactin levels increase)
Hypopituitarism
What does growth hormone deficiency lead to in children and adults?
Children - short stature
Adults - reduce quality of life
What does a gonadotropin deficiency result in?
- delayed puberty in children
- loss of secondary sexual characteristic in adults
- loss of periods is an early sign for women
When can gonadotropin deficiency be commonly seen in men?
When using chemotherapy to treat prostate cancer, the drug inhibits testosterone
When can TSH and ACTH deficiencies occur?
They’re a late feature of pituitary tumours
What does TSH deficiency present as?
- low thyroid hormones
- cold
- weight gain
- tiredness
- slow pulse
- low T4
- non-elevated TSH
What does ACTH deficiency present as? What can it result in?
- low cortisol
- tiredness
- dizziness
- low BP
- low sodium
- HPA axis will be affected
Hypoadrenal crisis which is life threatening
Which hormones are usually produced in excess when there’s abnormality in pituitary function?
Which are produced in excess more rarely?
- prolactin
- GH
- ACTH
- TSH
- LH/FSH
What biochemical assessment do you carry out to assess pituitary disease affecting the thyroid axis, gonadal axis and prolactin axis?
A basal blood test
What biochemical assessment do you carry out to assess pituitary disease affecting the HPA axis, GH axis?
A dynamic blood test may be needed
Why does it matter when you do a blood test to asses the HPA axis?
Testing for cortisol levels - levels of cortisol vary throughout the day (usually tested at 9am when levels are at higher levels)
What is a dynamic blood test?
When you activate/suppress a hormonal axis and observe the response
When would you suppress and when would you stimulate in a dynamic assessment of HPA and GH axes?
Stimulate when suspected hormone deficiency
Suppress when suspected hormone excess
What do you stimulate and suppress for a dynamic assessment of the HPA/adrenal axis?
Stimulate adrenals by ACTH (using a synthetic form) or insulin stress test - induce hypoglycaemic stress by giving insulin by IV - usually hypoglycaemic stress should activate the HPA axis
Suppress ACTH axis with steroids
What do you stimulate and suppress for a dynamic assessment of the GH axis?
Stimulate using the insulin stress test (should stimulate GH release)
Suppress using the glucose tolerance test (increase blood glucose as increased blood glucose reduces GH release)
How do you do a radiological assessment of pituitary disease?
Use MRI
What is a bi-temporal hemi-anopia suggestive of?
A pituitary tumour
What is a prolactinoma?
A prolactin-secreting pituitary tumour
When is a tumour considered a macro-adenoma or a micro-adenoma?
Macro-adenoma: more than 1cm
Micro-adenoma: less than 1cm
How are prolactinomas treated?
With tablets, not an operation
What type of drug can you use to shrink a macro-prolactinoma?
A dopamine agonist as dopamine inhibits prolactin
