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Cushing's Syndrome

Cushing's syndrome refers to overproduction of cortisol caused by ACTH-producing pituitary corticotropic tumors("Cushing's disease"), ectopic ACTH-producing tumors, or ACTH-independent production of hormone by the adrenal gland Cushing's syndrome, Cushings syndrome, Cushing syndrome. Of these, Cushing's disease accounts for 70 to 80 percent of ACTH-dependent disease, and ectopic sources account for 15 to 20 percent of cases. Cushing's disease is

Adrenal tumors, including adenomas, carcinomas, and micronodular and macronodular hyperplasia, autonomously produce glucocorticoids and are found in 20 percent of patients with Cushing's syndrome. Overall, Cushing's syndrome is rare; the prevalence is estimated at about 

Clinical Presentation. The most common signs of Cushing's disease are a relatively sudden onset of central weight gain, frequent thickening of facial fat, which rounds the facial contour ("moon facies"), and a florid complexion due to telangiectasia. Other signs also accompany Cushing's syndrome (Table 16). An enlarged fat pad ("buffalo hump") accompanies any major weight gain and is not diagnostic, whereas increased fat pads that fill and bulge above the

Evaluation and Diagnosis. The evaluation of a patient with suspected endogenous glucocorticoid excess is divided into two steps: (1) initial screening and confirmatory tests to establish the diagnosis of clinically relevant endogenous glucocorticoid excess, and (2) localization of the source of hormone excess.

24-Hour Urinary Free CortisoI Excretion Rate. Measurement of the urinary free cortisol (UFC) excretion rate is the preferred diagnostic test. Previously, the 1-mg overnight dexamethasone (Decadron) suppression test (DST) was considered the screening test of choice but is now known to be less specific. Determination of the

Alcoholism and affective psychiatric disorders, e.g., major depression, may exhibit biochemical features of Cushing's syndrome and, therefore, decrease the reliability of test results. Most studies report a sensitivity of greater than


Signs and Symptoms of Cushing's Syndrome


Central obesity

Proximal muscle weakness



Psychiatric disorders


Wide purple striae (width greater than 1 cm)

Spontaneous ecchymoses

Facial plethora




Fungal skin infections

Endocrine and metabolic derangements

Hypokalemic alkalosis


Delayed bone age in children

Menstrual disorders, decreased libido, impotence

Glucose intolerance, diabetes mellitus

Kidney stones



Elevated white blood cell counts

particularly when multiple 24-hour urine collections are performed. UFC excretion rate values greater than 250 to 300 meg per dL per 24 hours determined on several occasions are considered diagnostic for

Treatment. When a clearly circumscribed microadenoma can be identified and removed, the treatment of choice for patients with Cushing's disease is transsphenoidal microadenomectomy. Otherwise, patients should

procedure fails, bilateral total adrenalectomy. For adult patients not cured by transsphenoidal surgery, pituitary irradiation is the most appropriate alternative.

In patients with nonpituitary tumors, resection cures the hypercortisolism; however, most tumors are nonresectable. Hypercortisolism can be