Screening Tests for Hypercortisolism – Adrenal Gland

00:02 Screening tests for hypercortisolism: dexamethasone suppression, low dose is 1 mg administered at night.

00:09 Normal individual will have suppressed, normal, okay, I am walking through this quickly because I already talked about it, everything that we talked about discussed is now in verbiage just to' for reinforcement purposes.

00:19 Patient with Cushing's syndrome will not suppress cortisol normally, syndrome maybe from the adrenal cortex.

00:28 The test is considered positive if the suppressed cortisol level is greater than 1.8 µg/dl Using the value 1.8 increases the tests sensitivity which is the desired characteristic for a screening test.

00:40 24 hour urine free cortisol measurement, 4 times upper limit of normal is diagnostic.

00:48 Screening tests for hypercortisolism, I went through just quickly, much of this we already discussed, make sure that it's firmly implanted in your head.

00:56 Now, I am going to get into more specificities about how to screen for hypercortisolism, this will be in current day practice, pay attention.

01:07 Salivary control, it is a sensitive screening test, loss of normal or diurnal variation usually precedes overt hypercortisolism.

01:18 Once again, loss of normal or diurnal, what does diurnal mean? Low at the end of the day, high in the morning of cortisol.

01:29 Relatively easy to do, but requires reliable labs, measures free hormone only.

01:35 Mildly abnormal screening results may represent pseudo-Cushing's.

01:38 Pseudo-Cushing's an important topic maybe due to depression or alcoholism.

01:45 How would you feel if you are depressed? Hmm, pretty lethargic, alcoholism, pretty lethargic; psychologically you might be a little varied.

01:56 Cushing's syndrome: summary of a lab test.

02:00 Adrenal cortisol producing, we have excess cortisol ACTH is undetectable.

02:08 What kind of hypercortisolism is this, please? Primary.

02:13 In Cushing's disease, most common endogenous case.

02:17 Here, we have excess cortisol due to excess ACTH, excess cortisol and ACTH is normal or high, excess cortisol suppression by high dose dexamethasone suppression test.

02:34 Ectopic ACTH producing tumor, I am going through this quickly since we have done it already.

02:39 Excess cortisol due to ACTH producing paraneoplastically by small cell lung cancer; excess not suppressed.

02:50 Excess cortisol, not suppressed, when do-when done or doing a high dose dexamethasone suppression test.

02:58 I have abbrevi-abbreviated as Dex.

03:03 Current day practice: this is a pathophysiology question that is being increasingly asked because people are so incredibly familiar with dexamethasone suppression test that you want to make sure that you have a full understanding of the hypothalamo, pituitary, adrenal access.

03:24 Let's take a look.

03:25 This is called CRH stimulation test.

03:28 CRH, go back to normal, corticotropin releasing hormone coming out of the hypothalamus works upon the anterior pituitary to release ACTH.

03:37 Watch this.

03:39 With vasopressin to ACTH dependent Cushing's syndrome, Cushing's disease, secondary hypercortisolism will respond, but ectopic ACTH production will not.

03:50 Let me recap that.

03:52 CRH stimulation test, why would you think about using this on your exam or with a patient? You have ACTH dependent tumors, two of them, what are they again? Anterior pituitary, ectopic' anterior pituitary, ectopic.

04:09 High dose dexamethasone suppression test is going to inhibit the cortisol from whom? From your anterior pituitary.

04:16 That's high dose dexamethasone.

04:19 If your CRH, corticotropin releasing hormone, what it will do is that with Cushing's disease, you will have a response with CRH stimulation test.

04:32 With ectopic, your hypothalamus has no control over what is going on in the lung.

04:39 So, ectopic ACTH production will not be influenced by CRH.

04:46 It helps you distinguish between the two ACTH dependent.

04:50 Next, discriminate between pseudo-Cushing's and Cushing's syndrome.

04:55 Pseudo-Cushing's refers to the following conditions: physical stress, visceral obesity, Poly Cystic Ovarian Syndrome, Anorexia Nervosa, psychologic stresses, symptoms that may seem a-a little similar perhaps to Cushing's, but it's pseudo.

05:13 So, therefore, important that you are able to distinguish between Cushing's versus