ACTH is typically increased in which disease?

• A. Adrenal insufficiency
• B. Primary hyperaldosteronism
• C. Cushing's disease
• D. Secondary adrenal crisis

Answer: (C)

Cushing's disease is characterized by an increase in adrenocorticotropic hormone (ACTH) levels due to a pituitary adenoma that produces excess ACTH. This leads to overproduction of cortisol by the adrenal glands, resulting in the clinical symptoms associated with Cushing's syndrome, such as obesity, hypertension, and purple striae. The condition is specifically linked to the excess ACTH that stimulates the adrenal cortex, exacerbating cortisol secretion.

In contrast, adrenal insufficiency, primary hyperaldosteronism, and secondary adrenal crisis typically involve different mechanisms that do not lead to elevated ACTH levels. For instance, in adrenal insufficiency, the adrenal glands fail to produce adequate corticosteroids, thereby causing a feedback mechanism that often results in increased ACTH levels, but the hallmark here is more about the insufficient corticostoid production. Primary hyperaldosteronism is characterized by excess aldosterone production without a corresponding increase in ACTH. Secondary adrenal crisis is associated with an acute drop in adrenal function usually triggered by stress or withdrawal from corticosteroid therapy, rather than a consistent elevation in ACTH levels, which is primarily a characteristic of Cushing's disease.