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.