Home Chapter Home Jobs Conferences Fellowships Books
Clinical chemistry
Adrenal insufficiency
Author: Renu Virk, M.D., University of Massachusetts Memorial Hospital (see Reviewers page)
Revised: 13 April 2010, last major update July 2009
Copyright: (c) 2009, PathologyOutlines.com, Inc.
Definition
=========================================================================
● Clinical condition which occurs when there is more than 90% destruction of the adrenal gland
Clinical Features
=========================================================================
● Often insidious in onset, patients may present in shock due to increased stress
● Malaise, lassitude, fatigue, weakness, anorexia, weight loss, nausea, vomiting, hypotension, hypoglycemia, hyponatremia, hyperkalemia and hyperpigmentation (with primary adrenal insufficiency)
● Morning serum cortisol level >13 mcg/dL reliably rules out adrenal insufficiency (J Fam Pract 2009;58:281a)
● Relative adrenal insufficiency: if patient's cortisol response is inadequate for the degree of illness or stress (J Perinatol 2009;29 Suppl 2:S44)
Acute Adrenal Crisis
=========================================================================
● Infection or major stress may transform chronic adrenal insufficiency into acute crisis
● Patient usually presents in shock
Primary Adrenal Insufficiency
=========================================================================
● See also Adrenal Gland chapter
● Chronic cases are also known as Addison’s disease
● Characterized by low morning serum cortisol, low morning salivary cortisol levels, high ACTH levels, low serum aldosterone levels, high plasma renin activity
● Note: late night (11 pm to midnight) salivary cortisol level testing is also useful (J Clin Endocrinol Metab 2009 Jul 14 [Epub ahead of print])
● Causes: amyloidosis, autoimmune adrenalitis, drugs, hemorrhagic infarction, infections (tuberculosis, histoplasmosis, HIV) that destroy substantial adrenal cortical tissue, metastases to adrenal gland, polyglandular autoimmune syndrome, radiation
Secondary and Tertiary Adrenal Insufficiency
=========================================================================
● See also Adrenal Gland chapter
● Due to pituitary (secondary) or hypothalamic (tertiary) disease
● Characterized by low ACTH levels, low morning serum cortisol, low morning salivary cortisol levels (Horm Metab Res 2009 Jul 7 [Epub ahead of print])
● Note: androgens and cortisol levels are low because their production is influenced by ACTH, but androgens are less affected in males since they are also produced by testis; hypoglycemia is more common than with primary adrenal insufficiency
● Serum aldosterone, sodium and potassium and plasma renin activity levels are usually normal, since they are controlled by renin-angiotensin axis, which is not under the control of ACTH
● Causes (secondary): panhypopituitarism, isolated ACTH deficiency (very rare); traumatic brain injury
● Causes (tertiary): chronic high dose glucocorticoid therapy, tumor, sarcoidosis, cranial irradiation
Laboratory
=========================================================================
● Low early morning serum cortisol levels (less than 3 mcg/dl)
●
Low basal urinary cortisol and 17-hydroxycorticosteroid levels
● Salivary cortisol value at 8 am < 1.8ng/ml or an early morning serum
cortisol level < 10 mcg/dl is suggestive of adrenal insufficiency
● Normal levels of morning salivary cortisol exclude adrenal insufficiency
● ACTH, aldosterone and plasma renin levels vary by cause (primary versus secondary / tertiary)
=========================================================================
● Patients with primary adrenal insufficiency show subnormal rise in cortisol after ACTH stimulation test
● This test may not detect partial secondary adrenal insufficiency
● 48-hour ACTH stimulation test reliably separates primary from secondary or tertiary adrenal insufficiency
● ACTH test is the single best test for confirming the diagnosis of chronic adrenal insufficiency (Lancet 1999;354:179)
=========================================================================
● Differentiates secondary from tertiary adrenal insufficiency
● Seldom used due to expense and a requirement for multiple blood samples
● Secondary - have subnormal results; Tertiary - normal response
● See also CRH stimulation test under Adrenal hypercortisolism
Insulin induced hypoglycemia and Metyrapone stimulation tests
=========================================================================
● More helpful if partial secondary/tertiary adrenal insufficiency is suspected
● Metyrapone test is less expensive
Additional references
=========================================================================
● Wikipedia, eMedicine #1; #2
End of Clinical Chemistry - Adrenal insufficiency
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, (c) 2001-2009, PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.com with any questions.