Terzolo et al listed criteria for the diagnosis of subclinical Cushing’s syndrome. The authors are from San Luigi Gonzaga Hospital and the University of Turin in Italy.


Criteria for subclinical Cushing’s syndrome:

(1) presence of an adrenal adenoma found incidentally (incidentaloma)

(2) no suspicion of adrenal disease prior detection of adrenal adenoma

(3) absence of a clear Cushingoid phenotype (although the patient may have facial roundness)

(4) autonomous cortisol secretion (ACTH-independent)


The patient may have:

(1) one ore more features of the metabolic syndrome

(2) osteoporosis

(3) a low serum ACTH

(4) urinary free cortisol concentration may be normal


Autonomous cortisol secretion is usually defined as an elevated serum cortisol after 1 mg overnight dexamethasone suppression test.

(1) Inadequate suppression is defined as a serum cortisol > 5 µg/dL (> 138 nmol/L).

(2) Adequate suppression (with subclinical Cushing syndrome excluded) is a serum cortisol < 50 nmol/L.(1.8 µg/dL).

(3) Serum cortisol levels between 50 and 138 nmol/L are indeterminate.


The diagnosis of subclinical Cushing’s syndrome should be suspected in a patient with indeterminate dexamethasone suppression if there are clinical features present (osteoporotic fractures, metabolic syndrome, etc).


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