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Cortisol, Free, Urine, 24-Hour
MessageSendout, Mayo test code: CORTU
Test Code
LAB382
Alias/See Also
Cortisol Free Urine
Free Urinary Cortisol
Urinary Free Cortisol
CORTU
Free Urinary Cortisol
Urinary Free Cortisol
CORTU
CPT Codes
82530
Preferred Specimen
5 mL urine from 24-hour urine collected in 10 g boric acid
Minimum Volume
3 mL
Instructions
1. Collect urine for 24 hours.
2. Add 10 g of boric acid as preservative at start of collection.
2. Add 10 g of boric acid as preservative at start of collection.
Transport Container
Plastic, urine tube
Transport Temperature
Refrigerated
Specimen Stability
Refrigerated (preferred): 14 days
Frozen: 28 days
Ambient: 7 days
Frozen: 28 days
Ambient: 7 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.
Methodology
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
FDA Status
Approved
Setup Schedule
Monday through Friday
Report Available
2-5 days
Limitations
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.
This test has limited usefulness in the evaluation of adrenal insufficiency.
This methodology (liquid chromatography-tandem mass spectrometry) eliminates analytical interferences including carbamazepine (Tegretol) and synthetic corticosteroids.
Renal disease (decreased excretion) may cause falsely low 24-hour urinary free cortisol values.
Improper collection may alter results. For example, a missed morning collection may result in false-negative tests; an extra morning collection (ie, >24 hours) may give false-positive results.
Twenty-four hour urinary free cortisol values may be elevated to twice the upper limit of the normal range during pregnancy.
Patients with exogenous Cushing syndrome caused by ingestion of hydrocortisone will not have suppressed cortisol values.
This test has limited usefulness in the evaluation of adrenal insufficiency.
This methodology (liquid chromatography-tandem mass spectrometry) eliminates analytical interferences including carbamazepine (Tegretol) and synthetic corticosteroids.
Renal disease (decreased excretion) may cause falsely low 24-hour urinary free cortisol values.
Improper collection may alter results. For example, a missed morning collection may result in false-negative tests; an extra morning collection (ie, >24 hours) may give false-positive results.
Twenty-four hour urinary free cortisol values may be elevated to twice the upper limit of the normal range during pregnancy.
Patients with exogenous Cushing syndrome caused by ingestion of hydrocortisone will not have suppressed cortisol values.
Reference Range
Included with report
Clinical Significance
Preferred screening test for Cushing syndrome.
Diagnosis of pseudo-hyperaldosteronism due to excessive licorice consumption.
Test may not be useful in the evaluation of adrenal insufficiency.
Diagnosis of pseudo-hyperaldosteronism due to excessive licorice consumption.
Test may not be useful in the evaluation of adrenal insufficiency.
Performing Laboratory
Mayo Clinic Laboratories, Rochester, Minnesota
Additional Information
Cortisol, Free, 24 Hour, Urine
