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Diagnosis of Cushing's syndrome

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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Diagnosis of Cushing's syndrome

Seek Expert Advice.

Who should be tested

 

Testing for Cushing's syndrome is recommended in the following groups (1):

 

  • Patients with unusual features for age (e.g. osteoporosis, hypertension)

 

  • Patients with multiple and progressive features, particularly those who are more predictive of Cushing's syndrome

Features that best discriminate Cushing's syndrome; most do not have a high sensitivity

easy bruising

facial plethora

proximal myopathy (or proximal muscle weakness)

striae (especially if reddish purple and > 1 cm wide)

on children, weight gain with decreasing growth velocity

Cushing's syndrome features in the general population that are common and/or less discriminatory

depression

dorsocervical fat pad ("buffalo hump")

fatigue

facial fullness

weight gain

obesity

back pain

supraclavicular fullness

changes in appetite

thin skin

decreased concentration

peripheral edema

decreased libido

acne

impaired memory (especially short term)

hirsutism or female balding

insomnia

poor skin healing

irritability

menstrual abnormalities

in children, slow growth

in children, abnormal genital virilization

in children, short stature

in children, pseudoprecocious puberty or delayed puberty

 

  • children with decreasing height percentile and increasing weight

 

  • patients with adrenal incidentaloma compatible with adenoma

 

The following tests are advised NOT to be used to test for Cushing's syndrome (1)

 

  • random serum cortisol or plasma ACTH levels

 

  • urinary 17-ketosteroids

 

  • insulin tolerance test

 

  • loperamide test

 

  • tests designed to determine the cause of Cushing's syndrome (e.g. pituitary and adrenal imaging, 8 mg DST)

 

For the initial testing for Cushing's syndrome, one of the following tests based on its suitability for a given patient, is recommended (1):

 

  • urine free cortisol (UFC; at least two measurements)

 

  • late-night salivary cortisol (two measurements)

 

  • 1-mg overnight dexamethasone suppression test (DST)

 

  • longer low-dose DST (2 mg/d for 48 h)

 

Diagnostic criteria that suggest Cushing's syndrome are UFC greater than the normal range for the assay, serum cortisol greater than 1.8 mug/dl (50 nmol/liter) after 1 mg dexamethasone (1-mg DST), and late-night salivary cortisol greater than 145 ng/dl (4 nmol/liter).

 

Subsequent evaluation based on expert advice

Reference:

  • Nieman LK et al. The Diagnosis of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline.J Clin Endocrinol Metab. 2008 May; 93(5): 1526-1540.

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