Home
HelpTest Code CRANR Cortisol, Free, Random, Urine
Ordering Guidance
The preferred screening test for Cushing syndrome is a measurement of free cortisol in a 24-hour urine collection by liquid chromatography tandem mass spectrometry (LC-MS/MS); order CORTU / Cortisol, Free, 24 Hour, Urine.
The optimal specimen type for evaluation of primary adrenal insufficiency and hypopituitarism is serum; order CORT / Cortisol, Serum.
Specimen Required
Supplies: Urine tube, 10 mL (T068)
Collection Container/Tube: Clean, plastic urine container with no metal cap or glued insert
Submission Container/Tube: Plastic, 10-mL urine tube or clean, plastic aliquot container with no metal cap or glued insert
Specimen Volume: 10 mL
Collection Instructions: Collect a random urine specimen.
Useful For
Investigating suspected hypercortisolism when a 24-hour collection is prohibitive (ie, pediatric patients)
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CRAN | Cortisol, Random, U | No | Yes |
| CRETR | Creatinine, Random, U | Yes, (order RCTUR ) | Yes |
Reporting Name
Cortisol, Free, Random, USpecimen Type
UrineSpecimen Minimum Volume
3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 14 days | |
| Frozen | 28 days | ||
| Ambient | 7 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.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 312=nmol/mol creatinine
Cortisol molecular weight=362.5
Creatinine molecular weight=113.12
Supportive Data
Multiple calibration curves for urinary cortisol and cortisone exhibited consistent linearity and reproducibility in the range of 7 to 828 nmol/L (0.25-30 mcg/dL). Inter-assay coefficients of variation were 7.3% to 16% for mean concentrations of 6 to 726 nmol/L (0.2-26.3 mcg/dL) for cortisol and cortisone. The detection limit was 6 nmol/L (0.2 mcg/dL). Recovery of cortisol and cortisone added to urine was 97% to 123%. The regression equation for the liquid chromatography tandem mass spectrometry (LC-MS/MS) (y) and high-performance liquid chromatography (x) method for cortisol was: y = 1.11x + 0.03 mcg cortisol/24 h (r(2) = 0.992; n = 99). The regression equation for the LC-MS/MS (y) and immunoassay (x) methods for cortisol was: y = 0.66x - 12.1 mcg cortisol/24 h (r(2) = 0.67; n = 99).(1)
Day(s) Performed
Monday through Friday
Report Available
2 to 6 daysSpecimen Retention Time
14 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
82530
82570
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CRANR | Cortisol, Free, Random, U | 44309-3 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 10328 | Cortisol/Creatinine Ratio | 11155-9 |
| CRETR | Creatinine, Random, U | 2161-8 |