Final answer:
The first-line test for suspecting Cushing syndrome is the 24-hour urinary-free cortisol level test, followed by the low-dose dexamethasone suppression test for confirmation.
Step-by-step explanation:
If you suspect Cushing syndrome, the first-line test is the 24-hour urinary-free cortisol level test. This test measures the amount of cortisol excreted in the urine over 24 hours. High levels of urinary-free cortisol can indicate Cushing syndrome.
The second test, often used to confirm the diagnosis, is the low-dose dexamethasone suppression test. In this test, the patient takes a low dose of dexamethasone, a synthetic glucocorticoid, which in normal individuals will suppress the secretion of cortisol by the adrenal glands. If cortisol levels do not drop sufficiently, Cushing syndrome may be present.
Cushing syndrome is characterized by symptoms such as obesity, diabetes, high blood pressure, and stretch marks in the skin. Treatments for Cushing syndrome aim to reduce excessive cortisol levels and may vary based on the underlying cause.