Acromegaly Flashcards
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
