Cushing syndrome

Cushing syndrome is the collection of disorders caused by prolonged exposure to excessive cortisol. It produces characteristic changes in metabolism, skin, muscle, bones, and cardiovascular function.

Cortisol: Cortisol is a steroid hormone made by the adrenal cortex that helps regulate metabolism, stress responses, and immune activity. Excess exposure to this hormone defines the syndrome and drives its effects.
Hypercortisolism: Hypercortisolism is excessive cortisol activity in the body, whether caused by disease or medication. It names the underlying hormonal state shared by the syndrome’s different causes.
Inferior petrosal sinus sampling: Inferior petrosal sinus sampling compares pituitary venous blood with peripheral blood to locate adrenocorticotropic hormone secretion. It can distinguish a pituitary source from ectopic hormone secretion when imaging is inconclusive.
Glucocorticoid-induced osteoporosis: Glucocorticoid-induced osteoporosis is reduced bone strength caused by prolonged glucocorticoid exposure. Cortisol excess accelerates bone loss and increases fracture risk.
Pseudo-Cushing state: A pseudo-Cushing state is a reversible pattern of cortisol-test abnormalities associated with conditions such as alcohol use disorder or severe depression. It can resemble the syndrome biochemically without autonomous cortisol excess.
Hypothalamic–pituitary–adrenal axis: The hypothalamic–pituitary–adrenal axis is the hormonal feedback system linking the hypothalamus, pituitary gland, and adrenal glands. Its feedback controls cortisol secretion and is disrupted differently across syndrome causes.
Cushingoid features: Cushingoid features are physical changes resembling Cushing syndrome, including central weight gain, facial rounding, and skin fragility. The features prompt evaluation but can occur without endogenous Cushing syndrome.
Pituitary MRI: Pituitary MRI is magnetic resonance imaging used to visualize the pituitary gland and nearby structures. It looks for a pituitary tumor after biochemical findings suggest an ACTH-dependent cause.
Steroid-induced diabetes: Steroid-induced diabetes is elevated blood glucose caused or worsened by glucocorticoid exposure. Cortisol raises glucose and reduces insulin sensitivity, sometimes producing diabetes.
Obesity: Obesity is excess body fat that can impair health and increase the risk of metabolic disease. It can share central weight gain and metabolic findings but does not establish cortisol excess.

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