Acromegaly

This is due to a pituitary tumour in almost all cases. Hyperplasia due to GHRH is rare.

Clinical features:

• Increased size of hands/feet
• Headaches
• Visual deterioration (especially loss of peripheral vision)
• Weight gain
• Amenorrhoea/oligomenorrhoea
• Galactorrhoea
• Impotence/poor libido
• Deep voice
• Excessive sweating
• Polyuria/polydipsia
• Prognathism
• HT

Investigations:

GH levels:

• Raised
• In normal adults, GH is usually <1mU/L

Glucose tolerance test:

• Is diagnostic
• Acromegalics fail to suppress GH below 1mU/L
• Some show a paradoxical rise in GH
• About 25% of acromegalics have a diabetic glucose tolerance test

IGF-1 level:

• Is almost always raided in acromegaly
• A single plasma level of IGF-1 reflects mean 24-hour GH levels and is useful in diagnosis

Visual field defects are common

MRI scans of the pituitary:

• Will almost always reveal the pituitary adenoma

Prolactin levels:

• Mild to moderate hyperprolactinaemia occurs in 30% of patients

Treatment:

Untreated, acromegaly results in markedly reduced survival with deaths from:

• Heart failure
• Coronary artery disease
• Hypertension-related causes

Surgery:

• Trans-sphenoidal surgery is generally agreed as the appropriate first-line therapy
• Results in clinical remission in a majority of cases (about 60%) with pituitary micro-adenoma, but only in a minority of those with macro-adenoma

External radiotherapy:

• Normally used after pituitary surgery fails to normalise GH levels rather than as a primary therapy
• It is combined with medium-term treatment with octreotide (a somatostatin analogue) or a dopamine agonist because of the slow biochemical response to radiotherapy, which may take 10 years or more