What test is used to confirm the diagnosis of Acromegaly apart from IGF-1 levels?

To confirm the diagnosis of acromegaly, the glucose suppression test is a critical assessment used alongside IGF-1 levels. In this test, the patient consumes a glucose solution, after which a growth hormone level is measured. In healthy individuals, glucose administration typically suppresses growth hormone secretion. However, in acromegaly, due to the presence of excess growth hormone production—often from a pituitary adenoma—growth hormone levels remain elevated even after glucose ingestion. This inability to suppress growth hormone in response to glucose is a hallmark sign of acromegaly and serves to validate the diagnosis established by elevated IGF-1 levels.

Other tests mentioned, like a chest X-ray, thyroid function tests, and an electrocardiogram, do not play a direct role in confirming acromegaly. A chest X-ray may be utilized to check for potential complications related to pituitary tumors, but it does not confirm acromegaly itself. Similarly, thyroid function tests evaluate thyroid hormone levels, and an electrocardiogram assesses heart conditions—neither of which provide specific insights into growth hormone regulation or the diagnosis of acromegaly. Thus, the glucose suppression test remains the principal confirming test beyond IGF-1 evaluation.