Acromegaly Flashcards
What is acromegaly?
A hormonal disorder in adults where theres an excessive of growth hormone (somatotrophin).
How does this impact the adult?
leads to continued growth of extremities - causing a large hands, feet and face.
What is the cause of acromegaly?
Secreting pituitary adenoma (benign).
What does the increased growth hormone do?
Causes excessive production of IGF-1 - causing inappropriate growth.
When does the hypothalamus release somatotrophin (GH releasing hormone)?
In response to low blood glucose levels.
increased exercise
increased stress
increased sleep
What limits growth hormone?
negative feedback
liver makes somatomedin signals
hypothalamus produces somatostatin (growth hormone inhibiting hormone)
What are the direct effects of GH?
Glucose is released into the blood from the liver
Muscles retain nitrogen (muscle growth)
Bone thickening (stimulating osteoblasts)
Increased insulin resistance (increased blood insulin levels).
What are the causes of acromegaly?
Pituitary adenoma - secreting GH.
Hypothalamic tumour - secreting GHRH.
Ectopic tumours - causing release of GH in other places.
Multiple endocrine neoplasia 1 (rare).
Which cancers have ectopic secreting GH tumours?
Rare.
Lung or pancreatic cancer.
What structure can be compressed in a pituitary tumour?
The optic chasm - causing bitemporal hemianopia.
What are the main symptoms of acromegaly?
Bitemporal hemianopia Frontal bossing (forehead and brow) Large nose Macro glossia Large hands Large feet Protruding jaw (prognathism) Arthritis Excessive sweating Increased organ size Congestive heart failure carpal tunel GI cancers from colon polyps Dental spacing erectile dysfunction Mood disturtabnces fatigue.
What are the complications of acromegaly?
bitemporal hemianopia
obstructive sleep apnoea
arthritis
increased prevalence of valvular heart disease
What should be done to follow up acromegaly?
Echocardiogram - increased risk of cardiomegaly and left ventricular failure.
Colonoscopy every 5 years - monitor for bowel polyps that might turn cancerous.
When is diagnosis made?
1st line - Increased IGF-1 and GI regardless of increased glucose.
2nd line - MRI
What is the treatment?
Transsphenoidal removal of pituitary adenoma.
Surgical removal of ectopic tumours
Pegvisomat (GH antagonist given subcutaneously daily)
Somatostatin analogues
Dopamine agonists (bromacriptine)
