How is a rapid adrenocorticotrophic hormone test performed in the workup of Addison disease?

Updated: Mar 11, 2020
  • Author: George T Griffing, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Answer

Performing the rapid adrenocorticotrophic hormone test [41]

  • Blood is drawn in 2 separate tubes for baseline cortisol and aldosterone values.

  • Synthetic ACTH (1-24 amino acid sequence) in a dose of 250 mcg (0.25 mg) is given IM or IV. Smaller doses of synthetic ACTH, as low as 1 mcg, have been used with accuracy approaching the standard test. Proponents of this modified test argue that a dose of 1 mcg or lower is more physiologic, whereas the 250-mcg dose is pharmacologic. However, the modified test is more sensitive only for the 30-minute samples, not the 60-minute samples.

  • Thirty or 60 minutes after the ACTH injection, 2 more blood samples are drawn; one for cortisol and one for aldosterone. No significant reason exists to draw both the 30-minute and 60-minute samples because the sensitivity of the 30-minute value for accurate diagnosis is well documented. The baseline and 30-minute samples usually are adequate to establish the diagnosis.


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