Which test is considered the most widely used screening method for Cushing's syndrome?

The overnight low-dose dexamethasone suppression test is widely recognized as the most common screening method for Cushing's syndrome due to its practicality and effectiveness in identifying patients with the condition. This test works on the principle of assessing the body's response to a synthetic glucocorticoid, dexamethasone, which normally suppresses adrenocorticotropic hormone (ACTH) and, subsequently, cortisol production.

In healthy individuals, administration of low doses of dexamethasone will lead to a decrease in cortisol levels, as the feedback mechanism signals the adrenal glands to reduce hormone production. However, in individuals with Cushing's syndrome, there is often a failure of this suppression because of excessive cortisol production, regardless of the influence of dexamethasone. High cortisol levels after administration indicate a dysfunction in this feedback loop, suggesting the presence of Cushing's syndrome.

While other tests such as corticotropin-releasing hormone stimulation test, petrosal sinus sampling, and metyrapone stimulation test have important roles in the diagnosis and differentiation of Cushing's syndrome and its etiology, they are not used as initial screening methods to the same extent as the overnight low-dose dexamethasone suppression test. Their more