Episode 7: What an Abnormal Dexamethasone Suppression Test Result Means: Interpreting Cortisol Results
A panelist discusses how abnormal dexamethasone suppression test (DST) results may indicate cortisol overproduction, emphasizing the importance of ruling out false-positive and false-negative results before proceeding to adrenal imaging for accurate diagnosis and targeted treatment.
By
Pamela Kushner, MD
| Published on June 18, 2025
2 min read
The following is an AI-generated summary based on the video content above:
An abnormal result from a DST typically indicates an issue with cortisol regulation, and it often warrants further investigation. When cortisol levels are not properly suppressed following the test, this could suggest conditions such as Cushing syndrome or other disorders affecting adrenal function. The lack of suppression points to potential overproduction of cortisol, which may be due to an adrenal tumor, a pituitary tumor producing excessive corticotropin (which stimulates cortisol release), or an ectopic source of corticotropin elsewhere in the body.
However, before concluding a diagnosis of cortisol excess, it is crucial to consider factors that may lead to false-positive results. Certain medications—such as estrogen therapies, seizure medications, or exogenous steroids—can interfere with the DST results. Pregnancy and individuals who rapidly metabolize dexamethasone may also present misleading outcomes. These factors should be ruled out before proceeding with further diagnostic workup to avoid misinterpretation.
False-negative results are also possible and may result from cyclic hypercortisolism, where cortisol levels vary unpredictably, making a single test potentially unreliable. Chronic liver disease, specific medications that inhibit the enzyme CYP3A4, and chronic kidney disease can all influence test outcomes, either by altering dexamethasone levels or interfering with cortisol metabolism. When cortisol excess is still suspected after accounting for these factors, the next appropriate step is imaging of the adrenal glands to identify the source of abnormal hormone production. This comprehensive approach ensures accurate diagnosis and guides the path for effective treatment.
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