investigations of acromegaly

Last reviewed 01/2018

The investigations in acromegaly should include:

• insulin-like growth factor 1 levels:
• a better test than growth hormone levels because IGF-1 levels are less variable
• also raised in pregnancy and puberty

• failure of growth hormone to be suppressed by 75 g oral glucose - false positive tests occur in poorly controlled diabetes mellitus, anorexia nervosa, hypothyroidism, Cushing's

• MRI / CT scan may reveal pituitary adenoma

• chest and abdominal radiology:
• to detect an ectopic source of growth hormone
• may detect cardiomegaly due to cardiomyopathy

• hands radiology reveals:
• tufting of terminal phalanges
• increased joint spaces due to cartilage hypertrophy

• assessment of pituitary function

• calcium - hypercalciuria is common in acromegaly due to a direct renal tubular action of growth hormone; if there is moderate or severe hypercalcaemia then this is suggestive of hyperparathyroidism (MEN-I)

• phosphate is often raised

Note that isolated GH measurement may show raised levels - however random levels are not diagnostic because levels vary with the time of day and other factors.