Testing:

There are a number of tests that can determine the presence of Cushing's disease, and distinguish the causative mechanism.

  • serum cortisol levels drawn at 8AM and 4PM

  • serum ACTH levels (early morning sample)

  • 24-hour urine for cortisol (a more precise test for true cortisol levels than the serum levels)

  • low-dose and high-dose dexamethasone suppression tests

  • FSH and LH levels (FSH=follicle-stimulating hormone; LH=

    luteinizing hormone)

  • CRH (corticosteroid releasing hormone) in combination with high-dose dexamethasone suppression testing

    If the results of low-dose dexamethasone testing do not suppress the cortisol levels, but the high-dose one does, this points to a pituitary tumor. If both suppress, then CRH testing should be done to rule in or out pseudo-Cushing's. (From my research, this is the most accurate method to distinguish pseudo-Cushing's from true Cushing's.)

    Then, if the results point to a pituitary tumor (which is the most common cause of Cushing's), an MRI scan of the brain is in order. This test is more effective and diagnostic than standard X-rays or brain scans in that it sees soft tissue better than conventional scans do.

    Most importantly.....

    FIND AN ENDOCRINOLOGIST WHO IS VERY FAMILIAR WITH PITUITARY ENDOCRINOLOGY.

    • The common garden-variety endocrinologist is most often involved mainly in diabetic or thyroid management. And if surgery is needed, find a neurosurgeon who has performed MANY transphenoidal tumor resections.

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