Pituitary tumours Flashcards
Which endocrine cells secrete growth hormone?
Somatrophs
Lactotrophs release which hormone?
Prolactin
Which endocrine cells secrete thyroid stimulating hormone?
Thyrotrophs
Which hormones are secreted by the gonadotrophs?
Luteinising hormone (LH) Follicle stimulating hormone (FSH)
Which cells secrete ACTH?
Corticotrophs
Acromegaly is related to which endocrine cell?
Somatotrophs
A tumour of the lactotrophs is referred to as?
Prolactinoma
A TSHoma is of what cell?
Thyrotrophs
What is a gonadotrophinoma?
Tumour of gonadotrophs
Which endocrine cells can be associated with Cushing’s disease?
Corticotroph adenoma
What is the classification of a microadenoma?
<1Omm (1cm)
What is the classification of a macroadenoma?
> 1cm (10mm)
What are the two types of a pituitary tumour in terms of function?
Excess secretion of a specific pituitary hormone
No excess secretion of pituitary hormone (non-functioning adenoma)
How is the mitotic index of a pituitary adenoma measured?
ki67 index benign is <3%
What mitotic index classifies a pituitary adenoma as benign?
<3%
Which hormone inhibits the pulsatile action of kisspeptin neurones?
Prolactin
What parameter of serum prolactin is associated with a prolactinoma?
> 5000mu/L
serum prolactin is proportional to tumour size
What are the clinical presentations of a prolactinoma?
menstrual disturbance erectile dysfunction Reduced libido Galactorrhoea Subfertility
What are the physiological causes of an elevated prolactin?
Pregnancy/breast feeding
Stress; exercise, seizure, venepuncture (stress induced can lead to an increase in prolactin levels)
Nipple/chest wall stimulation
What are the pathological causes of elevated prolactin?
Primary hypothyroidism (Due to increased TRH release) Polycystic ovarian syndrome Chronic renal failure
What are the latrogenic causes of elevated serum prolactin?
Antipsychotics Selective serotonin re-uptake inhibitors Anti-emetics High dose oestrogen opiates
What is macroprolactin?
A polymeric form of prolactin
An antigen-antibody complex of monomeric prolactin and IgG (normally <5% of circulating prolactin)
How is the majority of prolactin transported within the serum?
Monomeric prolactin that is biologically active
What are the two possible outcomes of an elevation of serum prolactin yet there are no clinical consistent features?
Macroprolactin
Stress of venipuncture
How can a stress of venepuncture be excluded from true elevation in serum prolactin?
Exclude by a cannulated prolactin series
Sequential serum prolactin measurement 20 minutes apart with an indwelling cannula to minimise venepuncture stress.
How is a true pathological elevation of serum prolactin diagnosed?
Conduct pituitary MRI
What is the first line of treatment in regards to prolactinomas?
Dopamine receptor agonists (cabergoline or bromocriptine)
What is the aim with using cabergoline?
Normalise serum prolactin and shrink prolactinoma
How do dopamine receptor agonists work?
Bind to D2 receptors on lacotrophs therefore exerting an inhibitory effect on prolactin release
What are the symptoms associated with acromegaly?
Sweatiness Headache Coarsening of facial features Macroglossia Prominent nose Large jaw - prognathism Increased hand and feet size Snoring & obstructive sleep apnoea Hypertension Impaired glucose tolerance/diabetes mellitus
Which factor is released from the liver upon stimulation of growth hormone?
IGF-1
and IGF-2
How can acromegaly be diagnosed?
Elevated serum IGF-1
Failed suppression of GH following oral glucose load (OGTT) - paraxodical rise
What is the main risk that is increased in patients with acromegaly?
Increased cardiovascular risk
What is the first line of treatment in patients with acromegaly?
Trans-sphenoidal pituitary surgery
What pharmacological treatments can be prescribed for acromegaly?
Somatosatin analogues (octreotide)
Dopamine agonists (cabergoline) -GH secreting pituitary tumours frequently express D2 receptors.
What are the clinical features Cushing’s syndrome?
Mental changes (depression) Osteoporosis Impaired glucose tolerance (diabetes) High blood pressure Proximal myopathy Red cheeks Fat pads Thin skin Easy bruising Moon face Purple striae Pendulous abdomen Poor wound healing
What is the most common cause of Cushing’s syndrome?
Oral corticosteroids
What are the four causes of Cushing’s disease?
Oral consumption of corticosteroids
Pituitary dependent Cushing’s disease (pituitary adenoma)
Ectopic ACTH (lung cancer)
Adrenal adenoma or carcinoma
What are ACTH dependent forms of Cushing’s disease?
Corticotroph adenoma Ectopic ACTH (lung cancer)
What are the ACTH independent causes of Cushing’s syndrome?
Oral corticosteroids
Adrenal adenoma or carcinoma
What is Cushing’s syndrome?
An excess cortisol
What is Cushing’s disease?
Due to corticotroph adenoma secreting ACTH
How is Cushing’s disease investigated?
Elevation of 24h urine free cortisol - increased cortisol secretion
Elevation of late light cortisol - salivary or blood test - loss of diurnal rhythm
Failure to suppress cortisol after oral dexamethasone (exogenous glucocorticoid) increased cortisol secretion.
What are the clinical features often presented alongside a non-functioning pituitary adenoma?
Bitemporal hemianopia
