Acromegaly
D E FI N I T ION
Constellation of signs and symptoms caused by hypersecretion of GH in
adults. (Excess GH before puberty results in gigantism.)
AE T IOLOGY
Most cases are a result of GH-secreting pituitary adenoma.
Rarely: Excess GHRH causing somatotroph hyperplasia from hypothalamic ganglioneuroma,
bronchial carcinoid or pancreatic tumours.
E P IDEMIOLOGY
Rare. Annual incidence of five in 1 000 000. Age at diagnosis: 40–50
years.
H ISTORY
Very gradual progression of symptoms over many years (often only detectable on
serial photographs).
May complain of rings and shoes becoming tight.
" Sweating, headache, carpal tunnel syndrome.
Symptoms of hypopituitarism (hypogonadism, hypothyroidism, hypoadrenalism). Visual
disturbances (caused by optic chiasm compression).
Hyperprolactinaemia (irregular periods, # libido, impotence).
EXAMINA T I ON
Hands: Enlarged spade-like hands with thick greasy skin. Signs of carpal
tunnel syndrome (see Carpal tunnel syndrome). Pre-mature osteoarthritis (arthritis also
affects other large joints, temporomandibular joint).
Face: Prominent eyebrow ridge (frontal bossing) and cheeks, broad nose bridge, prominent
nasolabial folds, thick lips, " gap between teeth, large tongue, prognathism, husky
resonant voice (thickening vocal cords).
Visual field loss: Bitemporal superior quadrantanopia progressing to bitemporal hemianopia
(caused by pituitary tumour compressing the optic chiasm).
Neck: Multi-nodular goitre.
Feet: Enlarged.
INVE S T I G A T IONS
Serum IGF-1: Useful screening test. GH stimulates liver IGF-1 secretion
(IGF-1 varies with age of patient and " during pregnancy and puberty).
Oral glucose tolerance test: Failure of suppression of GH after 75 g oral glucose load (falsepositive
results are seen in anorexia nervosa, Wilson’s disease, opiate addiction).
Pituitary function tests: 9 a.m. cortisol, free T4 and TSH, LH, FSH, testosterone (in men) and
prolactin (to test for hypopituitarism).
MRI of the brain: To image the pituitary tumour and effect on the optic chiasm.
MANAGEMENT
Surgical: Trans-sphenoidal hypophysectomy is the only curative
treatment.
Radiotherapy: Adjunctive treatment to surgery.
Medical: If surgery is contra-indicated or refused.
SC somatostatin analogues (octreotide, lanreotide). Side-effects: abdominal pain, steatorrhoea
glucose intolerance, gallstones, irritation at the injection site.
Oral dopamine agonists (bromocriptine, cabergoline). Side-effects: nausea, vomiting, constipation,
posturalhypotension ("dose graduallyandtake it during meals), psychosis (rare).
GH antagonist (pegvisomant)
Monitor: GH and IGF1 levels can be used to monitor disease control. Pituitary function tests,
echocardiography, regular colonoscopy and blood glucose.
COM P L IC A T I ONS
CVS: Cardiomyopathy, hypertension.
Respiratory: Obstructive sleep apnoea.
Gl: Colonic polyps.
Reproductive: Hyperprolactinaemia (30%).
Metabolic: Hypercalcaemia, hyperphosphataemia, renal stones, diabetes mellitus,
hypertriglyceridaemia.
ENDOCRINOLOGY
193
Acromegaly (continued)
Psychological: Depression, psychosis (resulting from dopamine agonist therapy).
Complications of surgery: Nasoseptal perforation, hypopituitarism, adenoma recurrence, CSF
leak, infection (meninges, sphenoid sinus).
P ROGNOS I S
Good with early diagnosis and treatment, although physical changes are
irreversible.
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