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HelpTest ID COCOU Cortisol/Cortisone, Free, 24 Hour, Urine
Secondary ID
82948Useful For
Screening test for Cushing syndrome (hypercortisolism)
Assisting in diagnosing acquired or inherited abnormalities of 11-beta-hydroxy steroid dehydrogenase (cortisol to cortisone ratio)
Diagnosis of pseudo-hyperaldosteronism due to excessive licorice consumption
This test has limited usefulness in the evaluation of adrenal insufficiency.
Special Instructions
Method Name
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Reporting Name
Cortisol/Cortisone, Free, USpecimen Type
UrineContainer/Tube: Plastic, 10-mL urine tube (T068)
Specimen Volume: 5 mL
Collection Instructions:
1. Collect urine for 24 hours.
2. Add 10 g of boric acid as preservative at start of collection.
Additional Information:
1. 24-Hour volume is required.
2. See Urine Preservatives in Special Instructions for multiple collections.
Urine Preservative Collection Options
|
Ambient |
No |
|
Refrigerated |
Yes |
|
Frozen |
Yes |
|
6N HCl |
No |
|
50% Acetic Acid |
Yes |
|
Na2CO3 |
No |
|
Toluene |
Yes |
|
6N HNO3 |
No |
|
Boric Acid |
Preferred |
|
Thymol |
No |
Specimen Minimum Volume
3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | 14 days |
| Frozen | 28 days | |
| Ambient | 72 hours |
Clinical Information
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-tandem 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.
Cortisone, a downstream metabolite of cortisol, provides an additional variable to assist in the diagnosis of various adrenal disorders, including abnormalities of 11-beta-hydroxy steroid dehydrogenase (11-beta HSD), the enzyme that converts cortisol to cortisone. Deficiency of 11-beta HSD results in a state of mineralocorticoid excess because cortisol (but not cortisone) acts as a mineralocorticoid receptor agonist. Licorice (active component glycyrrhetinic acid) inhibits 11-beta HSD and excess consumption can result in similar changes.
Reference Values
CORTISOL
0-2 years: not established
3-8 years: 1.4-20 mcg/24 hours
9-12 years: 2.6-37 mcg/24 hours
13-17 years: 4.0-56 mcg/24 hours
≥18 years: 3.5-45 mcg/24 hours
CORTISONE
0-2 years: not established
3-8 years: 5.5-41 mcg/24 hours
9-12 years: 9.9-73 mcg/24 hours
13-17 years: 15-108 mcg/24 hours
≥18 years: 17-129 mcg/24 hours
Use the factors below to convert each analyte from mcg/24 hours to nmol/24 hours:
Conversion factors
Cortisol: mcg/24 hours x 2.76=nmol/24 hours (molecular weight=362.5)
Cortisone: mcg/24 hours x 2.78=nmol/24 hours (molecular weight=360)
Cautions
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 methodology (liquid chromatography-tandem mass spectrometry) eliminates analytical interferences including carbamazepine (Tegretol) and synthetic corticosteroids.
This test has limited usefulness in the evaluation of adrenal insufficiency.
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.
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 and cortisone values.
Day(s) Performed
Monday through Saturday; 1 p.m.
Report Available
2 days (not reported on Sundays)Performing Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
82530-Cortisol; free
82542