Addison's Disease Testing
Addison's disease testing is crucial in determining whether a person does indeed have Addison's disease. Because symptoms can be very common and will appear gradually, it is important to have a health professional conduct a physical exam -- as well as several Addison's disease tests -- to determine results. Addison's disease testing may include ACTH stimulation tests, CRH stimulation tests, and abdominal x-rays.
In its early stages, it can be difficult to make an Addison's disease diagnosis. After asking a number of questions and performing a physical exam, the doctor may recommend certain tests as part of Addison's disease testing. These Addison's disease tests can include:
- ACTH stimulation test
- CRH stimulation test
- ACTH and cortisol blood levels
- Abdominal x-rays.
The ACTH stimulation test is the most specific test for diagnosing Addison's disease. In this test, blood cortisol, urine cortisol, or both, are measured before and after a synthetic form of ACTH is administered by injection.
In the so-called short, or rapid, ACTH test, measurement of cortisol in blood is repeated 30 to 60 minutes after an intravenous ACTH injection. The normal response after an injection of ACTH is a rise in blood and urine cortisol levels. Patients with Addison's disease respond poorly or do not respond at all.
When the response to the short ACTH test is abnormal, a "long" CRH stimulation test is required to determine the cause of adrenal insufficiency. In this test, synthetic CRH is injected intravenously, and blood cortisol is measured before and 30, 60, 90, and 120 minutes after the injection.
Patients with Addison's disease have high ACTHs but do not produce cortisol. Patients with secondary adrenal insufficiency have deficient cortisol responses but exhibit absent or delayed ACTH responses.