Screening Tests for Hypercortisolism – Adrenal Gland

by Carlo Raj, MD

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    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

    About the Lecture

    The lecture Screening Tests for Hypercortisolism – Adrenal Gland by Carlo Raj, MD is from the course Adrenal Gland Disorders.

    Included Quiz Questions

    1. 4x upper limit of normal
    2. 2x upper limit of normal
    3. 40x average normal
    4. 2x average normal
    5. 10x upper limit of normal
    1. Alcoholism
    2. Adrenal adenoma
    3. Cushing's disease
    4. Pituitary hyperplasia
    5. Loss of normal diurnal cortisol levels
    1. Undetectable ACTH
    2. Excess cortisol
    3. Normal or high ACTH
    4. Normal high-dose dexamethasone suppression test
    5. Elevated 24-hour urine cortisol levels
    1. Hypoparathyroidism
    2. Physical stress
    3. PCOS
    4. Major depressive disorder
    5. Anorexia nervosa

    Author of lecture Screening Tests for Hypercortisolism – Adrenal Gland

     Carlo Raj, MD

    Carlo Raj, MD

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