Acromegaly

Question 1

What is acromegaly?

Answer 1

Constellation of signs and symptoms caused by hypersecretion of GH in adults (Excess GH before puberty results in gigantism)

Question 2

What is the aetiology of acromegaly?

Answer 2

• Most cases are a result of GH-secreting pituitary adenoma - Rarely: Excess GHRH causing somatotroph hyperplasia from hypothalamic ganglioneuroma, bronchial carcinoid or pancreatic tumours

Question 3

What is the epidemiology of acromegaly?

Answer 3

• Rare - Age at diagnosis: 40-50

Question 4

What are the presenting symptoms of acromegaly?

Answer 4

• Very gradual progression of symptoms over many years - May complain of rings and shoes becoming tight - Increased sweating, headache, carpal tunnel syndrome - Symptoms of hypopituitarism (hypogonadism, hypothyroidism, hypoadrenalism) Visual disturbances (caused by optic chiasmm compression - Hyperprolactinaemia (irregular periods, reduced libido, impotence)

Question 5

What are the signs of acromegaly on examination?

Answer 5

• Hands: Enlarged spade-like hands with thick greasy skin. Signs of carpal tunnel syndrome. Premature oesteoarthritis (which also affects other large joints, temporomandibular joint) - Face: Prominent eyebrow ridge (frontal bossing) and cheeks, broad nose bridge, prominent nasolabial folds, thick lips, increased gap between teeth, large tongue, progathism, 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

Question 6

What are the investigations for acromegaly?

Answer 6

• Serum IGF-1: GH stimulates liver IGF-1 secretion - Oral glucose tolerance test: Failure of suppression of GH after 75h oral glucose load (false positive results seen in anorexia nervosa, Wilson’s disease, opiate addiction - Pituitary function tests: 9am 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

Question 7

How is acromegaly managed?

Answer 7

• Surgical: Trans-spenoidal hypophysectomy is the only curative treatment - Radiotherapy: Adjunctive treatment to surgery - Medical: If surgery is contra-indicated or reduced - SC somatostatin analogues (octreotide, lanreotide) Side effects: abdo pain, steatorrhoea glucose intolerance, gallstones, irritation at injection site - Oral dopamine agonists (bromocriptine, cabergoline) SE: nausea, vomiting, constipation, postural hypotension (raised dose gradually and take it during meals) psychosis - GH antagonist (pegvisomant) - Monitor: GH and IGF1 levels can be used to monitor disease control. Pituitary function tests, echocardiography, regular colonoscopy and blood glucose

Question 8

What are the possible complications of acromegaly?

Answer 8

• CVS: cardiomyopathy, hypertension - Respiratory: Obstructive sleep apnoea - GI: colonic polyps - Reproductive: Hyperprolactinaemia - Metabolic: Hypercalcaemia, Hyperphosphataemia, renal stones, diabetes mellitus, Hypertriglyceridaemia - Psychological: Depression, psychosis (resulting from dopamine agonist therapy) - Complications of surgery: Nasoseptal perforation, hypopituitarism, adenoma recurrence, CSF leak, infection (meninges, sphenoid sinus)

Question 9

What is the prognosis for acromegaly?

Answer 9

Good with early diagnosis and treatment, although physical changes are irreversible