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Test Code CORT U Cortisol, Free, Random, Urine

Reporting Name

Cortisol, Free, Random, U

Useful For

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


Specimen Required


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

Specimen Volume: 5 mL

Collection Instructions: Collect a random urine specimen.


Specimen Type

Urine

Specimen Minimum Volume

3 mL

Specimen Stability Information

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

RCTU: Enzymatic Colorimetric Assay

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

Method Description

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)

Reference Values

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

≥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

≥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

CPT Code Information

82530

LOINC Code Information

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

 

Result ID Test Result Name Result LOINC Value
10328 Cortisol/Creatinine Ratio 11155-9
RCTU Creatinine Conc 2161-8

Profile Information

Test ID Reporting Name Available Separately Always Performed
RCTU Creatinine Conc No Yes
CRAN Cortisol, Random, U No Yes

Reject Due To

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

NA