Final answer:
The appropriate test for a patient with abnormally low levels of cortisol is the Adrenocorticotropic hormone (ACTH) stimulation test, which assesses the adrenal glands' capacity to produce cortisol and helps diagnose adrenal insufficiency or Addison's disease.
Step-by-step explanation:
For a patient with abnormally low levels of cortisol, the Adrenocorticotropic hormone (ACTH) stimulation test would be appropriate. This test involves administering synthetic ACTH and measuring the cortisol response from the adrenal glands. If the adrenal glands produce cortisol in response, it suggests they are functioning normally; a lack of response may indicate adrenal insufficiency, also known as Addison's disease. The ACTH stimulation test is diagnostic of the adrenal glands' ability to produce cortisol and helps differentiate between primary and secondary adrenal insufficiency.
It’s important to note that Dexamethasone suppression tests are often used in the context of diagnosing Cushing's syndrome, which is characterized by abnormally high levels of cortisol, and is not the correct choice for testing low cortisol levels. The parathyroid hormone (PTH) stimulation test is unrelated, as it deals with calcium metabolism, and there is no such test as the Dexamethasone activation test referenced in this context.