Cushing Syndrome and Addison Disease

Cushing syndrome is chronic cortisol excess. The source may be excess ACTH from a pituitary adenoma or ectopic tumour, which stimulates both adrenal glands, or an adrenal tumour producing cortisol independently of ACTH. Exogenous glucocorticoids can produce the same clinical state and are a common, preventable explanation for apparent Cushing syndrome. Cortisol is meant to help the body meet stress: it supports vascular tone, raises glucose availability, alters immune activity, and affects fat and protein metabolism. Persistent excess turns these short-term adaptations into harm. Muscle protein breaks down, producing proximal weakness and thin, fragile skin. Fat distribution changes, glucose rises, blood pressure increases, and bone loss accelerates. Addison disease is primary adrenal insufficiency caused by adrenal cortex destruction, most often autoimmune. The adrenal glands cannot produce sufficient cortisol or aldosterone. Low cortisol leaves the patient unable to maintain an adequate stress response. Low aldosterone causes renal sodium loss and potassium retention, reducing effective circulating volume. The ACTH response separates primary adrenal failure from many other causes of fatigue and hypotension. With Addison disease, the pituitary releases large amounts of ACTH...