Nursing care
Cushing syndrome vs Cushing disease: what is the difference?
Written and reviewed by Nicole Ramirez, BSN, RN, CMSRN · 4 min read · Updated November 2026
Short answer
Cushing syndrome is the set of signs caused by long-term excess cortisol or similar glucocorticoids, whatever the source. Cushing disease is one cause of that syndrome: a pituitary tumor making too much ACTH. The most common cause of the syndrome overall is long-term glucocorticoid medicine, not a tumor, and the clinical signs look the same either way.
The single distinction: the source of the cortisol
Think of the syndrome as the picture and the disease as one possible reason for it. MSD Manuals defines Cushing syndrome as the clinical effects of chronically high cortisol or related glucocorticoids, and Cushing disease as the form caused by excess pituitary ACTH. Every patient with Cushing disease has Cushing syndrome, but most people with the syndrome do not have the disease.
The causes sort into groups. Glucocorticoid medicines taken long term at high doses are the most common cause overall, according to NIDDK. Among cases not caused by medicine, NIDDK reports that ACTH-secreting pituitary tumors cause about 8 out of 10. The rest come from ACTH made by tumors outside the pituitary, such as small cell lung cancer, or from adrenal adenomas or carcinomas.
Signs are shared, so the body cannot tell you the cause
The physical findings come from cortisol, so they appear whichever source is responsible. MSD Manuals lists moon face, truncal obesity, a buffalo hump, striae, thin limbs with muscle wasting, easy bruising and hypertension. High blood glucose, poor wound healing, infection risk and mood changes follow from the same excess.
A common student mistake is to pick a physical sign as proof of a pituitary tumor. No single sign does that. NIDDK notes that no one test is perfect, so clinicians usually use two screening tests, such as a 24-hour urine cortisol, a late-night salivary cortisol or a dexamethasone suppression test, to confirm excess cortisol before hunting for the source.
How the cause is found: ACTH points the way
Once excess cortisol is confirmed, an ACTH level helps separate the causes. When an adrenal tumor makes cortisol on its own, the high cortisol suppresses pituitary ACTH. When a pituitary or ectopic tumor drives the adrenals, ACTH is not suppressed. MSD Manuals describes petrosal sinus sampling for cases where pituitary and ectopic sources remain hard to separate.
Medicine-induced Cushing syndrome needs no tumor search, which is why the medication history comes first. NIDDK advises that steroid-induced cases are managed by the prescriber gradually lowering the dose to the lowest that controls the underlying condition. Stopping glucocorticoids suddenly is the dangerous error, because the suppressed adrenals cannot respond to stress.
Nursing care that differs by cause
For Cushing disease, treatment usually means pituitary surgery, often through the nose, and the nursing focus shifts to that surgery: watching for clear nasal drainage, changes in urine output that could suggest diabetes insipidus, and teaching about hormone replacement afterward. The linked pituitary surgery page covers those steps in detail.
For medicine-induced Cushing syndrome, the nursing work is teaching: never stop steroids abruptly, report signs of infection early, and follow the taper exactly as prescribed. For all causes, monitor blood glucose, blood pressure, skin integrity and fall risk from muscle weakness, and use infection precautions because high cortisol blunts the usual signs of infection.
Hypothetical practice scenario
Hypothetical scenario, not a real exam item: a client with rheumatoid arthritis has taken prednisone for two years and now has a round face, purple abdominal striae and new hyperglycemia. The client asks whether this means a brain tumor. Which response by the nurse is most accurate?
The best answer explains that the long-term steroid medicine is the most common cause of these changes, and that the prescriber will decide whether any further testing is needed. Saying it is Cushing disease is the tempting distractor, because the name sounds right, but that term means a pituitary tumor making ACTH. Advising the client to stop the prednisone is unsafe.
Sources and further reading
MSD Manual Professional Version: Cushing Syndrome. Definitions of Cushing syndrome and Cushing disease, causes including ectopic ACTH and adrenal tumors, clinical signs, diagnostic tests including ACTH levels and petrosal sinus sampling, pituitary surgery.
NIDDK: Cushing's Syndrome. Glucocorticoid medicines as most common cause, pituitary tumors causing about 8 in 10 non-medicine cases, symptoms, use of two screening tests, gradual dose reduction for steroid-induced cases.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our endocrine practice questions are the closest set to what this page covers.
Common questions
What is the difference between Cushing syndrome and Cushing disease?
Cushing syndrome describes the effects of too much cortisol from any source. Cushing disease is the specific form caused by a pituitary tumor making excess ACTH. All Cushing disease is Cushing syndrome, but not the other way around.
What causes Cushing disease?
A pituitary tumor, usually a noncancerous adenoma, that secretes too much ACTH. The extra ACTH drives the adrenal glands to make excess cortisol. NIDDK reports these tumors cause about 8 in 10 cases of Cushing syndrome not caused by glucocorticoid medicines.
What are the signs of Cushing syndrome?
Weight gain around the trunk, a round face, a fat pad behind the neck, thin arms and legs, purple stretch marks, easy bruising, muscle weakness, high blood pressure and high blood glucose. Women may notice irregular periods and extra facial hair.