Most common cause of Cushing’s syndrome is
**Question:** Most common cause of Cushing's syndrome is
A. Hypercortisolism
B. Adrenocorticotropic hormone (ACTH) tumor
C. Pituitary adenoma
D. Exogenous corticosteroid use
**Correct Answer:** C. Pituitary adenoma
**Core Concept:** Cushing's syndrome is a condition characterized by elevated cortisol levels due to excessive ACTH production. ACTH is a hormone secreted by the anterior pituitary gland, which stimulates cortisol production by the adrenal glands.
**Why the Correct Answer is Right:** Cushing's syndrome is most commonly caused by a pituitary adenoma (tumor) secreting excessive ACTH. This leads to hypercortisolism (elevated cortisol levels) and the development of the clinical features associated with Cushing's syndrome.
**Why Each Wrong Option is Incorrect:**
A. Hypercortisolism: Although hypercortisolism is a feature of Cushing's syndrome, it is not the cause; rather, it is the result of excessive cortisol production.
B. Adrenocorticotropic hormone (ACTH) tumor: While an ACTH tumor can lead to Cushing's syndrome, the correct answer focuses on the pituitary adenoma secreting excessive ACTH, not an ACTH tumor itself.
D. Exogenous corticosteroid use: This refers to the consumption of synthetic corticosteroids, usually from medications, which can lead to Cushing's-like symptoms but is not the most common cause of the disease.
**Clinical Pearl:** Cushing's syndrome can be caused by various factors, including pituitary adenomas, adrenal tumors, and exogenous corticosteroid use. However, the most common cause is a pituitary adenoma producing excessive ACTH, leading to elevated cortisol levels and the characteristic clinical features of Cushing's syndrome.