What happens when your adrenal glands go into overdrive—or shut down entirely? Though opposite in effect, Addison’s disease and Cushing’s syndrome are both rooted in adrenal dysfunction, and their symptoms can be surprisingly misleading. In this article, we’ll explore the key differences in Addison’s disease vs Cushing’s—and why understanding them is crucial for proper diagnosis and treatment.
Take control of your health—Book with an adrenal gland disorders doctor now!
What Are the Causes of Addison’s Disease vs Cushing’s Syndrome
Addison’s disease and Cushing’s syndrome are both disorders related to the adrenal glands, but they arise from opposite problems—one from too little cortisol and the other from too much. Comprehending their causes helps clarify the contrast between these two conditions.
Addison’s Disease:
Also known as primary adrenal insufficiency, Addison’s disease occurs when the adrenal cortex is damaged and cannot produce enough cortisol—and sometimes aldosterone. The most common cause is autoimmune destruction, where the immune system mistakenly attacks the adrenal glands. Other potential causes include infections such as tuberculosis, adrenal hemorrhage, genetic disorders, or the sudden withdrawal of long-term corticosteroid therapy. In all these cases, the result is an underproduction of essential hormones that help regulate stress response, metabolism, and blood pressure.
Cushing’s Syndrome:
Cushing’s syndrome, by contrast, is caused by prolonged exposure to high cortisol levels. This may result from external sources, such as the extended use of corticosteroid medications, or internal causes, such as hormone-secreting tumors. The most common internal cause is Cushing’s disease, where a pituitary adenoma produces excess ACTH (adrenocorticotropic hormone), overstimulating the adrenal glands. Other sources include adrenal tumors or ectopic ACTH-secreting tumors, which may be found in the lungs or other tissues.
The Key Tests to Diagnose Addison’s vs Cushing’s
Diagnosing each condition relies on specific hormonal tests that assess adrenal gland function and detect hormone imbalances. Though both conditions involve cortisol, the testing methods differ based on whether cortisol levels are too low (Addison’s) or too high (Cushing’s).
Tests for Addison’s Disease:
- ACTH Stimulation Test: Synthetic ACTH is administered to check cortisol response. In Addison’s, cortisol remains low despite stimulation.
- Blood Tests: May show low sodium, high potassium, and elevated ACTH—indicating the body is trying to stimulate the adrenal glands unsuccessfully.
- Imaging (CT scan): Used to detect adrenal gland damage or structural abnormalities.
Tests for Cushing’s Syndrome:
- 24-Hour Urinary Free Cortisol Test: Measures cortisol in urine collected over a full day; elevated levels suggest Cushing’s.
- Late-Night Salivary Cortisol Test: Assesses cortisol levels at night, which should normally be low—high levels may indicate Cushing’s.
- Low-Dose Dexamethasone Suppression Test: A steroid pill is taken to see if it suppresses cortisol production. If not, Cushing’s is likely.
- Imaging (Pituitary MRI or Adrenal CT): Helps identify tumors responsible for excess hormone production.
These targeted tests are essential for distinguishing between Addison’s and Cushing’s and ensuring accurate diagnosis and treatment.
Cortisol Levels Differ in Addison’s Disease and Cushing’s
Cortisol is a steroid hormone produced by the adrenal glands that plays a main role in regulating metabolism, blood pressure, and the body’s response to stress. In both, cortisol levels are disrupted—but in opposite directions, leading to very different symptoms and health effects.
In Addison’s disease, cortisol levels are abnormally low. This happens because the adrenal glands are damaged and can’t produce enough hormones. As a result, individuals may experience fatigue, weight loss, low blood pressure (hypotension), and darkening of the skin. These symptoms reflect the body’s struggle to function without adequate cortisol.
In contrast, Cushing’s syndrome is marked by excess cortisol. This may result from the body producing too much cortisol or from long-term use of corticosteroid medications. Common signs include central weight gain, a rounded “moon” face, muscle weakness, high blood pressure, and fragile skin that bruises easily. These symptoms stem from the overstimulation of normal processes that cortisol typically helps regulate.
Can Addison’s Disease and Cushing’s Be Treated Similarly?
Although Addison’s disease and Cushing’s syndrome both involve dysfunction of the adrenal glands, their treatments are not similar. This is because the conditions stem from opposite problems—Addison’s involves too little cortisol, while Cushing’s results from too much.
Addison’s disease is treated by replacing the deficient hormones. Patients typically take daily oral corticosteroids such as hydrocortisone or prednisone to substitute for cortisol. If there’s also an aldosterone deficiency, fludrocortisone may be prescribed. During stress, illness, or surgery, patients often need to adjust their medication dosages to prevent an adrenal crisis, which can be life-threatening. Long-term management and patient education are essential for safely living with the condition.
In contrast, Cushing’s syndrome focuses on reducing excess cortisol levels. If the cause is a tumor in the pituitary, adrenal gland, or elsewhere, surgical removal is typically the first step. When surgery isn’t possible or doesn’t fully resolve the issue, radiation or medications that suppress cortisol production may be used. If Cushing’s is caused by long-term steroid use, treatment involves gradually tapering the medication under medical supervision.
Sources.
Fleseriu, M., & Petersenn, S. (2012). Medical management of Cushing’s disease: what is the future?. Pituitary, 15(3), 330-341.
Barthel, A., Benker, G., Berens, K., Diederich, S., Manfras, B., Gruber, M., … & Bornstein, S. R. (2019). An update on Addison’s disease. Experimental and Clinical Endocrinology & Diabetes, 127(02/03), 165-175.