The best initial test for acromegaly is a growth hormone stimulation test. This test measures the body’s production of growth hormone (GH) in response to an artificial stimulus. The test typically involves the administration of a drug, such as arginine or clonidine, to stimulate the release of GH. The patient’s GH levels are then measured before and after the drug stimulation. A high level of GH after stimulation indicates acromegaly. Other tests, such as IGF-1 (insulin-like growth factor-1) and GHBP (GH binding protein) levels, may also be measured to confirm diagnosis. In some cases, a CT scan or MRI may be used to evaluate the size and shape of the pituitary gland to determine if a tumor is present.
The growth hormone stimulation test is the most reliable and accurate test for diagnosing acromegaly, and is the best initial test to use. It is important to note, however, that a positive result on this test does not necessarily confirm the presence of acromegaly, and further tests may be necessary to confirm diagnosis.