If you have been diagnosed with Cushing’s by screening tests, additional testing will be necessary to determine the cause of your Cushing’s. These tests will include measurement of adrenocorticotropic hormone (ACTH) levels to distinguish between an ACTH-secreting pituitary tumor or an ectopic tumor (elevated ACTH levels) and a cortisol-secreting adrenal tumor (low ACTH levels). Suppressed ACTH levels may also be observed in patients who use glucocorticoid medications. More information can be found under Testing and in the Fact Sheet.
Pituitary Tumors and Ectopic Tumors
If ACTH is elevated, indicating a pituitary or ectopic tumor, imaging of the pituitary by MRI will be performed, as well as other tests, to distinguish between the two (see Testing and the Fact Sheet for more information). If a petrosal sinus sampling test is suggested, it should only be done at a center experienced in the procedure.
If the source of ACTH appears to be from a pituitary tumor, transsphenoidal pituitary surgery to remove the tumor is recommended. It is extremely important that pituitary surgery be done by an experienced pituitary surgeon; thus, many patients travel to specialty facilities for surgery. Use of an experienced pituitary surgeon improves the surgical success rate, decreases complications, and can often preserve normal pituitary function. The Pituitary Society website has more information on pituitary surgery and surgeons. Also see the surgery section of Doctor’s Articles and the pituitary tumors and surgery section of Doctor’s Answers on this website.
If ACTH is elevated and is suspected to be ectopic, a whole body imaging procedure will likely be done. If the tumor can be located, it most likely will be surgically removed. More information on ectopic tumors can be found in the ectopic Cushing’s section of Doctor’s Articles and in the ectopic Cushing’s section of Doctor’s Answers. If the tumor cannot be located, medications will most likely be used to lower or block cortisol.
If ACTH is low, indicating an adrenal tumor, imaging of the adrenal glands by CT will be done. Most adrenal tumors involve a tumor on a single gland; however, there are disorders that involve both glands. Surgery for most adrenal tumors can be done laparoscopically and involves the removal of the affected adrenal gland. Your physician will refer you to a surgeon who has experience with adrenalectomies. More information can be found in the patient information section of the American Association of Endocrine Surgeons website and in the adrenal tumor section of Doctor’s Answers on this website.
By far the most common cause of Cushing’s symptoms is the use of glucocorticoid medications to treat other medical conditions. These can include oral medications, such as hydrocortisone, prednisone and dexamethasone, as well as injections given in joints, inhalers, and topical creams. You should work with your physician to investigate other treatment options for the medical problem that necessitated the use of steroids, and you should be referred to an endocrinologist. NEVER stop steroid medications without consulting a physician as this could result in life-threatening adrenal insufficiency. More information is in this article on Medication Induced Cushing’s and in the Medication-induced Cushing’s section of Doctor’s Answers. If you need to take steroids long term, the book, Coping With Prednisone could be a valuable resource.