Home Chapter Home Jobs Conferences Fellowships Books
Advertisement
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
=========================================================================
● Disorder of chronic exposure to high levels of cortisol in the blood, either endogenous or exogenous
Terminology
=========================================================================
● 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
=========================================================================
● Adrenal adenoma (eMedicine) or hyperplasia
● Adrenal carcinoma
● ACTH secreting pituitary adenoma (Cushing’s disease)
● Other tumors with ectopic ACTH production
● Exogenous glucocorticoids
Clinical features
=========================================================================
● 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
=========================================================================
Physical features Patient described by Buffalo hump
Dr. Harvey Cushing
Diagnosis
=========================================================================
● 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
=========================================================================
● Increase in daily urinary cortisol excretion
● High midnight salivary cortisol levels
● Increase in late evening serum cortisol levels
Low dose dexamethasone suppression test
=========================================================================
● 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
=========================================================================
● 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
=========================================================================
● Makes the dexamethasone test more sensitive
● Urinary and salivary cortisol should be measured twice (N Engl J Med 1986;314:1329)
=========================================================================
● 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
=========================================================================
Diagnostic algorithm for Cushing’s Syndrome
Gross images
=========================================================================
Adrenal adenoma
Additional references
=========================================================================
End of Clinical Chemistry > Adrenal Tests > Hypercortisolism
This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must also be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.
All information on this website is protected by copyright of PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.com with any questions (click here for other contact information).