Acromegaly is a condition caused by excess growth hormone. Almost all cases are due to a pituitary tumour.
Classical features include:
- Soft tissue growth (large hands, coarsening of features etc)
- Hyperhydrosis
- Headaches
- Parasthesia
- Hypertension
- Impaired glucose tolerance/diabetes
- Hoarse voice
MRCP smaller-print features include:
- Colonic polyps
- Proximal myopathy
- Arthralgia
- Raised triglycerides
- Osteopenia
- Cardiomegaly – up to 90% in long-term patients
- OSA
Diagnosis is by the failure of GH to decrease to less than 1 microgram/l 2 hrs after an oral glucose challenge of 75g. False positives may occur in pregnancy, diabetics, renal/hepatic impairment, obesity or those on oestrogen therapy.
Serum IGF-1 is raised but this is only useful for screening.
Treatment:
- Transphenoidal surgery – 50-70% cure
- Octreotide = somatostatin analogue – 70% efficacy – causes gallstones in 30%...
- Pegvisomant = competitive GH receptor antagonist – 80% effective
- Radiotherapy – but takes up to 20 yrs(!) to work
- Dopamine agonists – bromocriptine not believed to be effective; cabergoline works in less than 10%
Small print gem: IGF1 is the target hormone for GH and mediates most of GH’s growth-promoting actions. 80% of IGF1 is made in the liver.
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