North American Veterinary Licensing Examination (NAVLE) Practice Test

The ACTH stimulation test is considered the most reliable for diagnosing hyperadrenocorticism, particularly in dogs. This test measures the adrenal glands' response to adrenocorticotropic hormone (ACTH) stimulation. In a healthy animal, administration of ACTH should induce a modest increase in cortisol levels due to stimulation of cortisol production by the adrenal glands.

In cases of hyperadrenocorticism, however, there is typically an exaggerated or abnormal response, leading to significantly elevated cortisol levels following stimulation. This response is indicative of the condition and thus provides a reliable means of diagnosis.

On the other hand, while the Low Dose Dexamethasone Suppression test can also be utilized to diagnose hyperadrenocorticism, it can sometimes yield misleading results due to various physiological responses in the body, making it less definitive than the ACTH stimulation test. The Urine Cortisol Creatinine Ratio can indicate increased cortisol levels but is not specific enough to confirm the diagnosis of hyperadrenocorticism. Complicated enzymatic assays may provide some information but are not as commonly utilized in clinical practice compared to the ACTH stimulation test.