Pituitary Flashcards
What are the arteries right lateral to pituitary gland?
Internal carotid arteries
What is a physically active hormone produced from pituitary? (that does not have to act on something else to produce effect)
Prolactin
Its secretion is consistently inhibited (tonic inhibition) by hypothalamic dopamine
What does baseline pituitary function test involve?
9am cortisol
TSH, free thyroxine, free T3
Prolactin
LH/FSH (oestradiol for F, 9 am testosterone for M) - LH and FSH would be a bit high in post-menopausal F
IGF-1 (GH surrogate)
Urine and osmolality
What is a dynamic test for ACTH/cortisol and how does it work?
For chronic ACTH deficiency, adrenal gland would shrink, hence upon synthetic ACTH (synacthen) injection, cortisol response would be low on observation
But for acute adrenal damage, 9am cortisol is more suitable
What does hypopituitarism lead to?
GHD - growth failure in kids
TSH - secondary hypothroidism
LH/FSH - hypogonadropic hypogonadism
ACTH - secondary hypoadrenal
ADH deficiency - arginine vasopressin deficiency (diabetes insipidus) *might be a serious condition
How are hormones replaced?
Hydrocortisone - 2 to 3 times a day
Thyroxine
Sex steroids
GH (SC injection)
ADH - Desmopressin tablets/nasospray
What are causes of hypopituitarism?
Pituitary tumours
Non-pituitary brain tumours
Brain injury/damage
Iatrogenic
Granulomatous disease
Presentation of macro non-functioning pituitary adenomas?
Function: Hypopituitarism/hyperprolactinaemia
ACTH deficiency
TSH deficiency
LH/FSH deficiency hypothyroidism
GH deficiency
raised prolactin
Size:
Compression of optic chiasm or cavernous sinuses
How to manage macro non-functioning pituitary adenomas?
Trans-sphenoidal surgical resection
Prolactinoma
Commonest functioning pituitary tumour
Common in young woman (but overall M=F)
Infertility
1st-line Mx: Cabergoline (dopamine agonists)
*Would lead to effective shrinkage of giant prolactinomas (the shrinkage may also cause some effects like CSF leakage which need to be acted on)
Raised prolactin can be due to various reasons (unless extremely extremely raised, which would be prolactinoma)
Pharmacological reasons might be intake of dopamine receptor inhibitors
What are the range of symptoms of acromegaly?
Thickened soft tissues
Obstructive sleep apnoea
Arthropathy
Cardiovascular morbidity
etc
Cushing’s syndrome
Pituitary (majority) = Cushing’s DISEASE (65% of all Cushing’s)
Cortisol secreting adrenal tumour (independent of ACTH)
Ectopic ACTH production (usually related to cancer)
These need to be differentiated from physiological hypercortisolaemia
What are the features of excess cortisol/mineralocorticoid/androgen?
Excess cortisol
- protein loss
*myopathy; wasting
*osteoporosis;fracture
Screening of Cushing’s
*Overnight dexamethasone suppression test (oral)
*Urinary free cortisol
*Diurnal cortisol variation
(loss of diurnal variation suspicious of Cushing’s)
Diagnostic test of Cushing’s
Low dexamethasone suppression test dose (48 hr test starting from 9am)
Once confirmed from this - measure ACTH to check if it is dependent of it
ACTH undetectable/low – ACTH independent
ACTH normal/high – ACTH dependent
Apoplexy management
Pituitary function (for cortisol, just check point value)
MRI
Formal visual field assessment
Treat acute hormone deficits *eg emergency steroid dosing
Conservative vs surgical management dependent on clinical features
Hypophysitis
Inflammation of the pituitary gland (more commonly now as more monoclonal antibodies are used to treat cancer - a side effect)
Autoimmune
Systemic inflammation
Medication
Infection
Arginine vasopressin deficiency
This is due to deficiency in production of AVP in posterior pituitary
AVP resistance would be a nephrogenic problem
- Differentiate by doing water deprivation test using desmopressin
