Acromegaly Flashcards
(19 cards)
Pathophysiology?
There is an excess of growth hormone
Most common cause?
95% of cases are caused by a pituitary adenoma
Other causes?
- Ectopic GHRH
- GH production by tumours e.g. pancreatic
Symptoms?
- coarse facial appearance, spade-like hands, increase in shoe size
- large tongue, prognathism, interdental spaces
- excessive sweating and oily skin: caused by sweat gland hypertrophy
What other symptoms may be present if caused by a pituitary tumour?
- hypopituitarism
- headaches
- bitemporal hemianopia
What other hormone is raised in 1/3 of cases?
Prolactin leading to galactorrhoea
What is the main investigation? What is used to confirm the diagnosis after this
Serum IGF-1 levels.
An oral glucose tolerance test (OGTT) with serial GH measurements is used to confirm the diagnosis if IGF-1 levels are raised.
What may the results of an oral glucose tolerance test show?
- in normal patients GH is suppressed to < 2 mu/L with hyperglycaemia
- in acromegaly there is no suppression of GH
- may also demonstrate impaired glucose tolerance which is associated with acromegaly
What investigation can be performed to look for a pituitary tumour?
Pituitary MRI
1st line treatment?
Trans-sphenoidal surgery
What other treatments are available?
- Dopamine agonists
- Somatostatin analogues
- GH receptor antagonists
What do somatostatin analogues do?
Directly inhibit the release of growth hormone. May be used as an adjunct to surgery.
Example of a somatostatin analogue?
Octreotide
Example of a GH receptor antagonist?
Pegvisomant
How effective is the GH receptor antagonist?
Very effective as it decreases IGF-1 levels in 90% of patients back to normal, however it doesn’t reduce tumour volume so surgery is still needed if mass effect
When is external irradiation used?
It is sometimes used for older patients or following failed surgical/medical treatment
Complications?
- hypertension
- diabetes (>10%)
- cardiomyopathy
- colorectal cancer
Example of a dopamine agonist?
Bromocriptine
How effective are dopamine agonists?
Only effective in a minority of patients are are now superseded by somatostatin analogues
