Diagnosis of Cushing's syndrome
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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