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Test Code U24 Cortisol Cortisol, Free, 24 Hour, Urine

Reporting Name

Cortisol, Free, U

Useful For

Preferred screening test for Cushing syndrome

 

Diagnosis of pseudo-hyperaldosteronism due to excessive licorice consumption

 

This test has limited usefulness in the evaluation of adrenal insufficiency


Necessary Information


24-Hour volume is required.



Specimen Required


Supplies: Urine Tubes, 10-mL (T068)

Submission Container/Tube: Plastic, 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: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.


Specimen Type

Urine

Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 14 days
  Frozen  28 days
  Ambient  7 days

Day(s) and Time(s) Performed

Monday through Friday; 4 p.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

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

Method Description

Deuterated cortisol (d3-cortisol) is added to a 0.1-mL urine specimen as an internal standard. Cortisol, cortisone, and d3-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), d3-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)

Reference Values

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

 

Use the factor below to convert from mcg/24 hours to nmol/24 hours:

 

Conversion factor

Cortisol: mcg/24 hours x 2.76=nmol/24 hours (molecular weight=362.5)

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

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CORTU Cortisol, Free, U In Process

 

Result ID Test Result Name Result LOINC Value
8546 Cortisol, U 14158-0
TM93 Collection Duration 13362-9
VL47 Urine Volume 3167-4

Reject Due To

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

NA

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