NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Discrimination between primary and secondary adrenal insufficiency
Differential diagnosis of Cushing syndrome
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Cortrosyn Stimulation Test
Dexamethasone Suppression Test
Cortrosyn Stimulation Test
Dexamethasone Suppression Test
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Preferred: Serum gel
Acceptable: Red top
Specimen Volume: 0.6 mL
Collection Instructions: Morning (8 a.m.) and afternoon (4 p.m.) specimens are preferred.
1. Include time of draw.
2. If multiple specimens are drawn, send separate order for each specimen.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Mild OK; Gross reject
Mild OK; Gross OK
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Serum||Refrigerated (preferred)||7 days|
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Cortisol, the main glucocorticoid (representing 75%-90% of the plasma corticoids) plays a central role in glucose metabolism and in the body's response to stress.
Cortisol levels are regulated by adrenocorticotropic hormone (ACTH), which is synthesized by the pituitary in response to corticotropin-releasing hormone (CRH). CRH is released in a cyclic fashion by the hypothalamus, resulting in diurnal peaks (6 a.m.-8 a.m.) and nadirs (11 p.m.) in plasma ACTH and cortisol levels.
The majority of cortisol circulates bound to cortisol-binding globulin (CBG-transcortin) and albumin. Normally, <5% of circulating cortisol is free (unbound). The "free" cortisol is the physiologically active form. Free cortisol is filterable by the renal glomerulus.
Although hypercortisolism is uncommon, the signs and symptoms are common (eg, obesity, high blood pressure, increased blood glucose concentration). The most common cause of increased plasma cortisol levels in women is a high circulating concentration of estrogen (eg, estrogen therapy, pregnancy) resulting in increased concentration of cortisol-binding globulin.
Spontaneous Cushing syndrome results from overproduction of glucocorticoids as a result of either primary adrenal disease (adenoma, carcinoma, or nodular hyperplasia) or an excess of ACTH (from a pituitary tumor or an ectopic source). ACTH-dependent Cushing syndrome due to a pituitary corticotroph adenoma is the most frequently diagnosed subtype; most commonly seen in women in the third through the fifth decades of life. The onset is insidious and usually occurs 2 to 5 years before a clinical diagnosis is made.
Causes of hypocortisolism are:
-Addison disease-primary adrenal insufficiency
-Secondary adrenal insufficiency:
-Congenital adrenal hyperplasia-defects in enzymes involved in cortisol synthesis
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
a.m.: 7-25 mcg/dL
p.m.: 2-14 mcg/dL
In primary adrenal insufficiency, adrenocorticotropic hormone (ACTH) levels are increased and cortisol levels are decreased; in secondary adrenal insufficiency, both ACTH and cortisol levels are decreased.
When symptoms of glucocorticoid deficiency are present and the 8 a.m. plasma cortisol value is <10 mcg/dL (or the 24-hour urinary free cortisol value is <50 mcg/24 hours), further studies are needed to establish the diagnosis. First, the basal plasma ACTH concentration should be measured, followed by the short cosyntropin stimulation test. Other frequently used tests are the metyrapone, and insulin-induced hypoglycemia test. Consult the Endocrine Testing Center at 800-533-1710 extension 4-2148 for testing information and interpretation of test results.
Cushing syndrome is characterized by increased serum cortisol levels. However, the 24-hour urinary free cortisol excretion is the preferred screening test for Cushing syndrome, specifically CORTU / Cortisol, Free, Urine that utilizes high-performance liquid chromatography/triple quadrupole-mass spectrometry (LC-MS/MS). A normal result makes the diagnosis unlikely.
When cortisol measurement by immunoassay gives results that are not consistent with clinical symptoms, or if patients are known to or suspected of taking exogenous synthetic steroids, consider testing by LC-MS/MS; see CINP / Cortisol, Serum, LC-MS/MS. For confirming the presence of synthetic steroids, order SGSS / Synthetic Glucocorticoid Screen, Serum.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Acute stress (including hospitalization and surgery), alcoholism, depression, and many drugs (eg, exogenous cortisones, anti-convulsants) can obliterate normal diurnal variation, affect response to suppression/stimulation tests, and cause elevated baseline levels.
Patients taking prednisone may have falsely increased cortisol levels because prednisone is converted to prednisolone after ingestion and prednisolone has a 41% cross-reactivity.
Cortisol levels may be increased in pregnancy and with exogenous estrogens.
Some patients with depressive disorders have a hyperactive hypothalamic-pituitary-adrenal axis, similar to Cushing syndrome.
For patients taking exogenous glucocorticoids, order CORTU / Cortisol, Free, Urine
NOT RECOMMENDED for evaluating response to metyrapone; DOC / 11-Deoxycortisol, Serum is more reliable.
A low plasma cortisol level does not give conclusive indication of congenital adrenal hyperplasia. DOC / 11-Deoxycortisol, Serum; OHPG / 17-Hydroxyprogesterone, Serum; and DHEA_ / Dehydroepiandrosterone (DHEA), Serum provide a better, accurate, and specific determination of the enzyme deficiency.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Findling JW, Raff H: Diagnosis and differential diagnosis of Cushing's syndrome. Endocrinol Metab Clin North Am 2001;30(3):729-747
2. Buchman AL: Side effects of corticosteroid therapy. J Clin Gastroenterol 2001;33(4):289-294
Method Description Describes how the test is performed and provides a method-specific reference
The instrument used is a Beckman Coulter UniCel DxI 800. The Access Cortisol assay is a competitive binding immunoenzymatic assay. A specimen is added to a reaction vessel with rabbit antibody to cortisol, cortisol-alkaline phosphatase conjugate, and paramagnetic particles coated with goat anti-rabbit capture antibody. Cortisol in the specimen competes with the cortisol-alkaline phosphatase conjugate for binding sites on a limited amount of specific anti-cortisol antibody. Resulting antigen:antibody complexes bind to the capture antibody on the solid phase. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials washed away. Then the chemiluminescent substrate Lumi-Phos 530* is added to the reaction vessel and light generated by the reaction is measured with a luminometer. The light production is inversely proportional to the amount of cortisol in the specimen. The amount of analyte in the specimen is determined from stored, multi-point calibration curve.(Package insert: Access Cortisol, Beckman-Coulter, Brea, CA 2007)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; 5 a.m.-12 a.m., Saturday; 6 a.m.-6 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Same day/1 day
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|