What tests can help diagnose adrenal insufficiency?

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In its early stages, adrenal insufficiency can be difficult to diagnose. A review of a patient's medical history and symptoms may lead a doctor to suspect Addison's disease.

A diagnosis of adrenal insufficiency is confirmed through laboratory tests. The aim of these tests is first to determine whether levels of cortisol are insufficient and then to establish the cause. Radiologic exams of the adrenal and pituitary glands are also useful in helping to establish the cause.

Adrenocorticotropic hormone (ACTH) stimulation test
The ACTH stimulation test is the most commonly used test for diagnosing adrenal insufficiency. In this test, blood cortisol or urine cortisol or both are measured before and after a synthetic form of ACTH is given through an injection. The normal response after an ACTH injection is a rise in blood and urine cortisol levels. People with Addison's disease or long-standing secondary adrenal insufficiency have a little or no increase in cortisol levels.

Both low- and high-dose ACTH stimulation tests may be used depending on the suspected cause of adrenal insufficiency. For example, if secondary adrenal insufficiency is mild or of recent onset, the adrenal glands may still respond to ACTH because they have not yet atrophied. Some studies suggest that a low dose-1 microgram-may be more effective in detecting secondary adrenal insufficiency because a low dose is still enough to raise cortisol levels in healthy people but not in people with mild or recent secondary adrenal insufficiency.

Corticotropin-releasing hormone (CRH) stimulation test
When the response to the ACTH test is abnormal, the CRH stimulation test can help determine the cause of adrenal insufficiency. In the CRH stimulation test, synthetic CRH is injected intravenously and blood cortisol is measured before after the injection and 30, 60, 90, and 120 minutes after the injection. People with Addison's disease respond by producing high levels of ACTH but no cortisol. People with secondary adrenal insufficiency have absent or delayed ACTH responses. CRH will not stimulate ACTH secretion if the pituitary is damaged. So, an absent ACTH response points to the pituitary as the cause. A delayed ACTH response points to the hypothalamus as the cause.

This information is based on source information from the National Institute of Diabetes and Digestive and Kidney Diseases.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.