Dr. Adriana Ioachimescu gave an introduction to Cushing’s and diagnostic testing. She explained that normal cortisol levels are essential to life, but too much cortisol, over a period of time has devastating effects.
|Dr. Adriana Ioachimescu, Endocrinologist, Emory University, Atlanta, GA|
Dr. Ioachimescu discussed the causes of Cushing’s, including pituitary, adrenal and ectopic tumors, steroid medications (including steroid injections), and other conditions that can elevate cortisol, such as alcoholism or untreated sleep apnea and psychiatric disease. Of those affected by a tumor that causes Cushing’s syndrome, approximately 80% are have an ACTH secreting pituitary tumor (also called Cushing’s disease). The remainder have adrenal and ectopic tumors.
She also discussed the normal functioning of the hypothalamic-pituitary-adrenal axis and how cortisol levels are controlled. Testing for Cushing’s involves understanding how this system operates.
The diagnosis of Cushing’s involves multiple tests interpreted by an experienced endocrinologist. Imaging should be done after the diagnosis since small incidental pituitary tumors that may not require surgery are seen in a large percentage of the population. She then discussed the elements of the clinical suspicion for Cushing’s and the 3 screening tests that are currently used (24hr urinary free cortisol, the low dose dexamethasone suppression test and bedtime salivary cortisol) and their caveats. Two abnormal test results are required for a diagnosis. Once this is established, testing moves toward identifying the cause of Cushing’s syndrome. Normal or elevated ACTH levels indicate a pituitary or ectopic tumor, while lower than normal ACTH levels indicate an adrenal problem. Subsequently, imaging studies are conducted. The IPSS test was also discussed. The diagnosis of Cushing’s requires time and multiple tests. If there was ever a disease where a second or third opinion is warranted, it is Cushing’s.