Your doctor will talk to you first about your medical history and your signs and symptoms. If your doctor thinks that you may have Addison's disease, you may undergo some of the following tests:
- Blood test. Measuring your blood levels of sodium, potassium, cortisol and ACTH gives your doctor an initial indication of whether adrenal insufficiency may be causing your signs and symptoms. A blood test can also measure antibodies associated with autoimmune Addison's disease.
- ACTH stimulation test. This test involves measuring the level of cortisol in your blood before and after an injection of synthetic ACTH. ACTH signals your adrenal glands to produce cortisol. If your adrenal glands are damaged, the ACTH stimulation test shows that your output of cortisol in response to synthetic ACTH is limited or nonexistent.
- Insulin-induced hypoglycemia test. Occasionally, doctors suggest this test if pituitary disease is a possible cause of adrenal insufficiency (secondary adrenal insufficiency). The test involves checking your blood sugar (blood glucose) and cortisol levels at various intervals after an injection of insulin. In healthy people, glucose levels fall and cortisol levels increase.
- Imaging tests. Your doctor may have you undergo a computerized tomography (CT) scan of your abdomen to check the size of your adrenal glands and look for other abnormalities that may give insight to the cause of the adrenal insufficiency. Your doctor may also suggest an MRI scan of your pituitary gland if testing indicates you might have secondary adrenal insufficiency.