Acromegaly

Growth hormone (GH) stimulates skeletal and soft tissue growth - GH excess therefore produces gigantism in children (if aquired before epiphyseal fusion) and acromegaly in adults

Aetiology

• Nearly always due to a GH-secreting pituitary adenoma

Clinical presentation

• Giant (before epiphyseal fusion)

• Thickened soft tissues - skin, large jaw, sweaty, large hands

• Snoring/sleep apnoea (thickened nasopharynx)

• Hypertension, cardiac failure → early CV death

• Headaches (vascular)

• Diabetes mellitus

• Local pituitary effects - visual fields, hypopituitarism

Investigations

• IGF1 - age and sex matched, nearly always raised

• Gold standard - GTT suppression test
• 75g oral glucose: check GH at 0, 30, 60, 90, 120 min
• Normally GH suppresses to <0.4 ug/l after glucose
• Acromegaly indicated if GH unchanged/no suppression or paradoxical rise

Others

• Visual field

• CT/MRI pituitary scan to check size of adenoma

• Pituitary function tests for other hormones

Management

Pituitary surgery

• Transsphenoidal approach first-line

• 90% cure if microadenoma

• 50% cure if macroadenoma

Radiotherapy

• Normally used after pituitary surgery fails to normalise GH levels

• Often combined with medium-term treatment using pharmacological management options

Pharmalogical treatment

• Somatostatin analogues e.g. sandostain LAR reduce GH in most patients, can be used before surgery to relieve symptoms and marginally improve outcome

• Dopamine agonists work in around 10-15% of patients; increased efficacy if co-secreting prolactin

• GH antagonist (Pegvisoman) decreases IGF-1 but tumour size does not decrease; last line in therapy as very expensive

Other features

• Cancer surveillance - colon and tubulo-villous adenoma

• Cardiovascular risk factors - BP, lipids, glucose

• Manage sleep apnoea

Complications

• GH excess can result in the formation of colon polyps and colon cancer - may be presenting feature

• Increased risk of hypertension and cardiac failure can lead to early CV death