Which test is used to measure the function of the adrenal glands?

The ACTH stimulation test is utilized to evaluate the function of the adrenal glands by assessing how well they respond to adrenocorticotropic hormone (ACTH). In this test, synthetic ACTH is administered, and blood samples are taken afterward to measure cortisol levels. An adequate response, reflected in elevated cortisol levels, indicates normal adrenal gland function. Conversely, a suboptimal rise in cortisol may suggest adrenal insufficiency or dysfunction. This test is particularly important in diagnosing conditions such as Addison's disease or adrenal insufficiency related to other endocrine disorders.

In contrast, the insulin tolerance test primarily assesses insulin sensitivity and the function of the pancreas, while the glucose tolerance test evaluates how well the body processes glucose. The cortisol suppression test is intended to determine how cortisol regulation is functioning, but it does not directly measure adrenal response to ACTH. Therefore, the ACTH stimulation test is specifically designed to assess the functionality of the adrenal glands, making it the most relevant choice in this context.