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Clinical Chemistry

Adrenal Tests

Hypercortisolism

 

Author: Renu Virk, M.D., University of Massachusetts Memorial Hospital (see Authors page)

Revised: 21 September 2012, last major update January 2010

Copyright: (c) 2009-2012, PathologyOutlines.com, Inc.

 

Definition

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● Disorder of chronic exposure to high levels of cortisol in the blood, either endogenous or exogenous

 

Terminology

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● Also called Cushing’s syndrome (see Adrenal Chapter)

Cushing’s disease refers to a pituitary adenoma that produces excess ACTH

Subclinical hypercortisolism: due to incidental adrenal masses that may secrete cortisol autonomously, with no signs or symptoms of hypercortisolism (Eur J Endocrinol 2009;160:87); associated with high prevalence of hypertension, diabetes mellitus (Eur J Endocrinol 2005;153:837), obesity, dyslipidemia and osteoporosis

 

Causes

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Adrenal adenoma (eMedicine) or hyperplasia

Adrenal carcinoma

ACTH secreting pituitary adenoma (Cushing’s disease)

● Other tumors with ectopic ACTH production

● Exogenous glucocorticoids

 

Clinical features

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Obesity (buffalo hump is characteristic), hypertension, glucose intolerance, moon facies, easy bruisability, striae, proximal muscle weakness, bone loss, osteonecrosis of femur head, menstrual irregularities

With androgen excess, females show virilization

Some patients may present with neuropsychological changes

 

Clinical features

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Physical features               Patient described by         Buffalo hump

                                                Dr. Harvey Cushing

 

Diagnosis

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A single test cannot be used to diagnose hypercortisolism

Primary hypercortisolism: high serum cortisol, low plasma ACTH

Secondary hypercortisolism: high serum cortisol, high plasma ACTH

 

Laboratory tests

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Increase in daily urinary cortisol excretion

High midnight salivary cortisol levels

Increase in late evening serum cortisol levels

 

Low dose dexamethasone suppression test

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Absence of suppression supports a diagnosis of Cushing’s syndrome (J Clin Endocrinol Metab 2006;91:2582), but suppression also occurs in some patients with Cushing’s syndrome (J Clin Endocrinol Metab 2004;89:1222)

This test is not very helpful in patients with abnormal levels of cortisol binding globulin

 

High dose dexamethasone suppression test

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This test is useful in differentiating primary hypercortisolism from ACTH secreting pituitary adenoma

No suppression is noted in patients with ectopic ACTH secretion or adrenal adenoma

 

CRH after dexamethasone test

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Makes the dexamethasone test more sensitive

Urinary and salivary cortisol should be measured twice (N Engl J Med 1986;314:1329)

 

CRH stimulation test

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Usually done with equivocal plasma ACTH levels

Indicated to differentiate Cushing’s disease from Cushing’s syndrome

Pituitary tumor will show increase in ACTH and cortisol levels

Adrenal tumor and ectopic ACTH production will not show any increase

● See also CRH stimulation test under Adrenal Insufficiency

 

Diagrams

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Diagnostic algorithm for Cushing’s Syndrome

 

Gross images

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Adrenal adenoma

 

Additional references

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Wikipedia, eMedicine

 

End of Clinical Chemistry > Adrenal Tests > Hypercortisolism

 

 

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