DST; ACTH suppression test; Cortisol suppression test
Cortisol levels should decrease after you receive dexamethasone.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
An abnormal response to the low-dose test may mean that you have abnormal release of cortisol (Cushing syndrome). This could be due to:
The high-dose test can help tell a pituitary cause (Cushing's disease) from other causes.
Abnormal results vary based on the condition causing the problem.
Cushing syndrome caused by an adrenal tumor:
Cushing syndrome related to an ectopic ACTH-producing tumor:
Cushing syndrome caused by a pituitary tumor (Cushing's disease)
Stewart PM. The adrenal cortex. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, PA: Saunders Elsevier; 2008: chap 14.
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