Cushing's Syndrome
Chronic glucocorticoid excess, usually caused by prescribed steroids, produces a recognisable catabolic and metabolic phenotype; endogenous disease needs specialist biochemical confirmation and source localisation.
Definition
Cushing's syndrome is chronic glucocorticoid excess. It is most commonly iatrogenic from exogenous steroids; endogenous disease is ACTH-dependent from a pituitary or ectopic source, or ACTH-independent from autonomous adrenal cortisol production.
First principles
Always distinguish exogenous from endogenous cortisol excess first
The commonest clinical cause of Cushing's syndrome is prescribed glucocorticoid exposure, including less obvious inhaled, topical, injected or repeated-course treatment. Endogenous disease is caused by autonomous cortisol production from the adrenal gland or by ACTH from a pituitary corticotroph adenoma (Cushing's disease) or an ectopic tumour. A careful medicines history prevents inappropriate endocrine testing and unsafe steroid withdrawal.
This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.