Acromegaly • Very rare • Prevalence in the order of 1 in 200,000 • Usually diagnosed between age 40 and 60 • No difference in gender susceptibility • Insidious onset
Pathogenesis • Most commonly caused by pituitary adenoma • Increased secretion of growth hormone • Acts in liver to release IGF-1 (insulin-like growth factor)
So what are the symptoms? • Tumour • Growth hormone • IGF-1
On examination • Characteristic facial appearance: Coarse, Frontal bossing, ↑sinuses, ↑ tongue, Prognathism (jaw protrusion), separation of teeth • Deep voice • Carpal tunnel syndrome • Hand & foot enlargement • Visual fields (bitemporalhemianopia) • Organomegaly: Goitre, Hepatosplenomegaly
Investigations • Glucose tolerance test with measurement of growth hormone level. • (Should be inhibited by glucose) • (Growth hormone secretion is episodic and so a random GH alone is unlikely to be useful) • Evidence of other pituitary involvement • MRI scan to identify adenoma
Management • Surgery: trans-sphenoidaladenomectomy or craniotomy for very large tumours. • Pituitary radiotherapy: useful if tumour is not fully removed and reduces GH progressively over years. • Drugs: • Somatostatin analogues (octreotide, lanreotide) suppress GH in 60% • Dopamine agonists (bromocriptine, cabergoline) lower but rarely normalize GH • GH receptor antagonist (pegvisomant) normalizes IGF-I in >90% of pts.
Bonus marks management Management of: • ↑ Cardiovascular morbidity & mortality – from HTN, impaired GTT (25%), Diabetes Mellitus (10%) • ↑ Cardiac failure (heart muscle disease), ↑IHD, ↑CVD • Obstructive sleep apnoea • Arthropathy (50%) • Osteoporosis • Colorectal cancer Complication of treatment: hypopituitarism