From the Guidelines
Yes, dexamethasone can be given with an Adrenocorticotropic hormone (ACTH) stimulation test in suspected adrenal insufficiency, as it does not cross-react with cortisol in most assays, allowing for an accurate test result. This approach is supported by the American Society of Clinical Oncology clinical practice guideline 1. The recommended dose of dexamethasone in this situation is 4 mg IV, which is preferred over hydrocortisone or other glucocorticoids when immediate treatment is needed.
To perform the ACTH stimulation test, the following steps can be taken:
- Draw a baseline cortisol level
- Administer 250 mcg of synthetic ACTH (cosyntropin) intravenously
- Collect cortisol samples at 30 and 60 minutes post-administration After completing the test, it is recommended to switch to hydrocortisone (100 mg IV every 8 hours) for ongoing treatment until results are available, as stated in the guideline 1.
The use of dexamethasone in this context is beneficial because it allows for the simultaneous treatment of potentially life-threatening adrenal insufficiency while still obtaining diagnostic information. This approach is particularly important in emergency situations where the diagnosis of adrenal insufficiency is suspected but not yet confirmed. The guideline emphasizes the importance of emergent therapy with dexamethasone in such cases, highlighting its suitability for use with an ACTH stimulation test 1.
Key points to consider:
- Dexamethasone does not cross-react with cortisol in most assays, making it suitable for use with an ACTH stimulation test
- The recommended dose of dexamethasone is 4 mg IV
- Hydrocortisone (100 mg IV every 8 hours) should be used for ongoing treatment after the test is completed
- Patients with suspected adrenal insufficiency require prompt treatment and diagnostic evaluation to confirm the diagnosis and guide further management, as outlined in the guideline 1.
From the FDA Drug Label
The plasma ACTH response to corticorelin injection is inhibited or blunted in normal subjects pretreated with dexamethasone.
Dexamethasone should not be given with an Adrenocorticotropic hormone (ACTH) stimulation test in suspected adrenal insufficiency, as it inhibits or blunts the plasma ACTH response to corticorelin injection 2.
From the Research
Dexamethasone and ACTH Stimulation Test
- Dexamethasone can be given with an Adrenocorticotropic hormone (ACTH) stimulation test in suspected adrenal insufficiency, as it does not interfere with the cortisol test 3.
- The ACTH stimulation test is commonly used to diagnose adrenal insufficiency, and dexamethasone can be used until the test can be administered 3.
- A study found that the ACTH stimulation test may be used for the diagnosis of suspected adrenal insufficiency within the first 3 days after initiation of empiric glucocorticoid therapy, including dexamethasone 4.
- The study suggested that an inadequate response of serum cortisol at 60 minutes to the ACTH stimulation test may be indicative of adrenal insufficiency in this setting 4.
Timing of ACTH Stimulation Test
- The timing of the ACTH stimulation test is important, and it is recommended to perform the test in the morning 5.
- A study found that the utility of a cortisol measurement 30 minutes after high-dose ACTH injection was low and did not add incremental diagnostic value to a single measurement after 60 minutes 6.
- The study suggested that a single cortisol value taken 60 minutes after ACTH stimulation is sufficient for the diagnosis of adrenal insufficiency 6.
Interpretation of ACTH Stimulation Test
- The interpretation of the ACTH stimulation test requires careful consideration of the clinical presentation and technical factors that can affect cortisol values and diagnostic accuracy 7.
- A case report highlighted the difficulties in diagnosing adrenal insufficiency and the importance of using the optimal dosing of cosyntropin during stimulation testing 5.
- The case report demonstrated that the use of the high-dose ACTH stimulation test performed in the early morning can help avoid lifelong steroid replacement therapy 5.