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Test ID: CRANU
Cortisol, Free, Random, Urine

Secondary ID A test code used for billing and in test definitions created prior to November 2011

82920

NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Useful For Suggests clinical disorders or settings where the test may be helpful

Investigating suspected hypercortisolism when a 24-hour collection is prohibitive (ie, pediatric patients)

Profile Information A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.

Test IDReporting NameAvailable SeparatelyAlways Performed
RCTUCreatinine ConcNoYes
CRANCortisol, Random, UNoYes

Method Name A short description of the method used to perform the test

RCTU: Enzymatic Colorimetric Assay

CRAN: Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name

Cortisol, Free, Random, U

Aliases Lists additional common names for a test, as an aid in searching

Cortisol Free Urine
Cortisol, Random, Urine
Free Cortisol
Free Urinary Cortisol
Urinary Free Cortisol

Specimen Type Describes the specimen type needed for testing

Urine

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.

Container/Tube: Plastic, 10-mL urine tube (Supply T068)

Specimen Volume: 5 mL

Collection Instructions: Collect a random urine 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.

3 mL

Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

NA

Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.

Specimen TypeTemperatureTime
UrineFrozen (preferred)14 days
 Refrigerated 7 days
 Ambient 72 hours

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Cortisol is a steroid hormone synthesized from cholesterol by a multienzyme cascade in the adrenal glands. It is the main glucocorticoid in humans and acts as a gene transcription factor influencing a multitude of cellular responses in virtually all tissues. Cortisol plays a critical role in glucose metabolism, maintenance of vascular tone, immune response regulation, and in the body's response to stress. Its production is under hypothalamic-pituitary feedback control.

 

Only a small percentage of circulating cortisol is biologically active (free), with the majority of cortisol inactive (protein bound). As plasma cortisol values increase, free cortisol (ie, unconjugated cortisol or hydrocortisone) increases and is filtered through the glomerulus. Urinary free cortisol (UFC) correlates well with the concentration of plasma free cortisol. UFC represents excretion of the circulating, biologically active, free cortisol that is responsible for the signs and symptoms of hypercortisolism.

 

UFC is a sensitive test for the various types of adrenocortical dysfunction, particularly hypercortisolism (Cushing syndrome). A measurement of 24-hour UFC excretion, by liquid chromatography-tandom mass spectrometry (LC-MS/MS), is the preferred screening test for Cushing syndrome. LC-MS/MS methodology eliminates analytical interferences including carbamazepine (Tegretol) and synthetic corticosteroids, which can affect immunoassay-based cortisol results.

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.

Males

0-2 years: 3.0-120 mcg/g creatinine

3-8 years: 2.2-89 mcg/g creatinine

9-12 years: 1.4-56 mcg/g creatinine

13-17 years: 1.0-42 mcg/g creatinine

> or =18 years: 1.0-119 mcg/g creatinine

 

Females

0-2 years: 3.0-120 mcg/g creatinine

3-8 years: 2.2-89 mcg/g creatinine

9-12 years: 1.4-56 mcg/g creatinine

13-17 years: 1.0-42 mcg/g creatinine

> or =18 years: 0.7-85 mcg/g creatinine

 

Use the conversion factors below to convert each analyte from mcg/g creatinine to nmol/mol creatinine.

 

Conversion factor

Cortisol: mcg/g creatinine x 413=nmol/mol creatinine

 

Cortisol molecular weight=362.5

Creatinine molecular weight=149.59

Interpretation Provides information to assist in interpretation of the test results

Most patients with Cushing syndrome have increased 24-hour urinary excretion of cortisol. Further studies, including suppression or stimulation tests, measurement of serum corticotropin (adrenocorticotropic hormone) concentrations, and imaging are usually necessary to confirm the diagnosis and determine the etiology.

 

Values in the normal range may occur in patients with mild Cushing syndrome or with periodic hormonogenesis. In these cases, continuing follow-up and repeat testing are necessary to confirm the diagnosis.

 

Patients with Cushing syndrome due to intake of synthetic glucocorticoids should have suppressed cortisol. In these circumstances a synthetic glucocorticoid screen might be ordered (SGSU / Synthetic Glucocorticoid Screen, Urine).

 

Suppressed cortisol values may also be observed in primary adrenal insufficiency and hypopituitarism. The optimal specimen type for evaluation of primary adrenal insufficiency and hypopituitarism is serum (CORT / Cortisol, Serum).

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Random urine cortisol results are less reliable than results obtained from properly collected and complete 24-hour urine specimens, which are not affected by diurnal variations in cortisol levels.

 

Acute stress (including hospitalization and surgery), alcoholism, depression, and many drugs (eg, exogenous cortisone, anticonvulsants) can obliterate normal diurnal variation, affect response to suppression/stimulation tests, and increase baseline levels.

 

Liquid chromatography-tandom mass spectrometry methodology eliminates analytical interferences including carbamazepine (Tegretol) and synthetic corticosteroids.

 

Random urine specimens may yield falsely elevated values when patients have a high urinary output.

 

Renal disease (decreased clearance) may cause falsely low values.

 

Values may be elevated to twice normal in pregnancy.

 

Patients with exogenous Cushing syndrome caused by ingestion of hydrocortisone will not have suppressed cortisol values.

Supportive Data

LC/MS/MS=1.09 (HPLC)-0.01

Correlation vs. Immunoassay Test CORTU / Cortisol, Free, 24 Hour, Urine

LC/MS/MS=0.65 (Immuno)-12.1

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;30:729-747

2. Boscaro M, Barzon L, Fallo F, Sonino N: Cushing's syndrome. Lancet 2001;357:783-791

3. Taylor RL, Machacek D, Singh RJ: Validation of a high-throughput liquid chromatography-tandem mass spectrometry method for urinary cortisol and cortisone. Clin Chem 2002;48:1511-1519

Method Description Describes how the test is performed and provides a method-specific reference

Deuterated cortisol (d[3]-cortisol) is added to a 0.1-mL urine specimen as an internal standard. Cortisol, cortisone, and d(3)-cortisol are extracted from the specimens using online turbulent-flow HPLC and analyzed by liquid chromatography-tandem mass spectrometry using multiple-reaction monitoring in positive mode. The following ion pairs are used for analysis: cortisol (363.0/121.1), cortisone (361.0/163.0), d(3)-cortisol (366.0/121.2). A calibration curve, generated from stripped urine spiked standards, is included with each batch of patient specimens.(Taylor RL, Machacek DA, Singh RJ: Validation of a high-throughput liquid chromatography-tandem mass spectrometry method for urinary cortisol and cortisone. Clin Chem 2002;48:1511-1519)

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information

No

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, Sunday; 1 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.

2 days

Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result

5 days

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

14 days

Performing Laboratory Location The location of the laboratory that performs the test

Rochester

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.

82530

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 IDReporting NameLOINC Code
10328Cortisol/Creatinine Ratio11155-9
RCTUCreatinine Conc2161-8