PITIUTARY TUMOURS Flashcards
What is a suprasellar macroadenoma?
A pituitary tumour which has grown out of the sella turcica
What is a non-functioning adenoma?
An adenoma which doesn’t cause any excess secretion of pituitary hormone
How can an adenoma causing hyperprolactinaemia lead to secondary hypogonadism?
Excess prolactin binds to kisspeptin neurones in hypothalamus and kisspeptin release is inhibited –> less GnRH, LH/FSH and testosterone/oestrogen
What is the most common functioning adenoma and what does it cause and present as?
Prolactinoma - usually serum prolactin > 5000mU/L
Menstrual disturbance, erectile dysfunction, reduced libido, subfertility, galactorrhoea
What are some other reasons why an elevated prolactin level is present?
Phsyiological - pregnancy, stress, nipple/chest wall stimulation
Pathological - primary hypothyroidism, polycystic ovarian syndrome, chronic renal failure
Latrogenic (drugs) - antipsychotics, SSSRIs, anti-emetics, high dose of oestrogen, opiates
What are the 2 reasons for an elevated serum prolactin if there are no clinical features consistent with this?
Macroprolactin - antigen-antibody complex of monomeric prolactin and IgG - sticky prolactin which gives high results
Stress of venepuncture - exclude by a cannulated prolactin series, overtime prolactin should fall if its just stress
What is the first-line treatment for a prolactinoma?
Dopamine receptor agonists - cabergoline
Binds to D2 receptors on lactotrophs
How is acromegaly diagnosed?
Failed suppression of GH after an oral glucose load (normally decreases GH - reasons unclear)
Elevated serum IGF-1
Pituitary MRI
Prolactin can be raised - co-secretion
What is the first-line treatment for acromegaly?
Trans-sphenoidal pituitary surgery which removes the tumour
Use somatostatin analogues/dopamine agonists prior surgery to shrink tumour or if surgical resection imcomplete
Radiotherapy
Give examples of ACTH dependent and ACTH independent Cushing’s syndrome?
ACTH dependent - cushing’s disease, ectopic ACTH (lung cancer)
ACTH independent - taking steroids by mouth, adrenal adenoma/carcinoma
What are some clinical features of Cushing’s disease?
Elevation of late night cortisol (loss of diurnal rhythm)
Elevation of 24hr urine free cortisol
Failure to suppress cortisol after oral dexamethasone
After confirmed hypercortisolism measure ACTH to see if ACTH dependent or independent
What problems can non-functioning adenomas result in?
Visual disturbance (bitemporal hemianopia)
Hypopituitarism
Raised serum prolactin as tumour blocks dopamine from travelling down pituitary stalk from hypothalamus to inhibit prolactin release
