What is the most common cause of Cushing syndrome?

NORCET 10 Mains

Medical & Surgical Nursing

Easy

Appeared in: NORCET 10 Mains

Explanation

The most frequent cause of Cushing syndrome is the administration of exogenous glucocorticoids, a situation known as iatrogenic Cushing syndrome.
This external cause is significantly more common than any endogenous (internal) cause originating from within the body.
It occurs in patients taking long-term, high-dose steroid medications for various inflammatory and autoimmune conditions.

Option B: A tumor of the adrenal cortex is an ACTH-independent endogenous cause of Cushing syndrome. While it leads to the syndrome, it accounts for only about 10% of endogenous cases, making it much less common than exogenous steroid use.
Option C: Increased ACTH from a pituitary tumor (Cushing's disease) is the most common endogenous cause of Cushing syndrome, accounting for about 70% of internal cases. However, the overall most common cause is exogenous steroid use.
Option D: Ectopic ACTH production, where a tumor outside the pituitary gland produces ACTH, is a relatively rare cause, accounting for about 15% of endogenous cases. It is far less common than exogenous steroid use.

Visual 1: Flowchart - A flowchart differentiating exogenous from endogenous causes. The endogenous branch should then split into ACTH-dependent (pituitary, ectopic) and ACTH-independent (adrenal) causes, with their relative frequencies.
Visual 2: Anatomical Diagram - An illustration showing the hypothalamic-pituitary-adrenal (HPA) axis. It should highlight the pituitary gland, the adrenal glands, and a potential ectopic site like the lungs to demonstrate the different origins of excess cortisol or ACTH.

Clinical Relevance

Nursing practice connection: Knowing Etiology and classification of Cushing syndrome helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses have a vital role in educating patients on long-term steroid therapy about the signs and symptoms of iatrogenic Cushing syndrome, such as weight gain, 'moon facies,' skin changes, and hyperglycemia.
A critical patient safety instruction is to never stop steroid medication abruptly, as this can lead to a life-threatening adrenal crisis. Tapering must be managed by a healthcare provider.
What if? If a patient on chronic steroids for lupus develops hypertension and central obesity, the nurse's priority action is to assess the patient, document the findings thoroughly, and report them to the prescribing physician. The answer is not to advise stopping the medication but to facilitate a medical review for a possible dose adjustment or management of the new symptoms.

How to Approach the Question

First, identify the key terms in the question: 'most common cause' and 'Cushing syndrome'.
Recognize this as a factual recall question that requires knowing the epidemiology of a disease.
Consider the options and categorize them. 'Exogenous steroid use' is an external (iatrogenic) cause. The other three options ('Tumor of adrenal cortex', 'Pituitary ACTH increase', 'Ectopic ACTH production') are all internal (endogenous) causes.
Recall or reason that conditions caused by medical treatment (iatrogenic) are often more common than the naturally occurring forms of the disease.
Differentiate between the 'most common cause overall' and the 'most common endogenous cause'. While pituitary tumors are the most common internal cause, they are still less frequent than the external cause.
Select 'Exogenous steroid use' as it is the most prevalent cause of Cushing syndrome in the general population.

Concept Tested & Keywords

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