Home
HelpTest Code LAB568 Cortisol, Free, 24 Hour, Urine
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Reporting Name
Cortisol, Free, USpecimen Type
UrineNecessary Information
24-Hour volume (in milliliters) is required.
Specimen Required
Supplies: Urine Tubes, 10-mL (T068)
Submission Container/Tube: Plastic urine tube
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 for multiple collections.
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 14 days | |
| Frozen | 28 days | ||
| Ambient | 7 days |
Specimen Minimum Volume
3 mL
Special Instructions
Day(s) Performed
Monday through Friday
Specimen Retention Time
14 daysReport Available
2 to 6 daysReference Values
0-2 years: Not established
3-8 years: 1.4-20 mcg/24 h
9-12 years: 2.6-37 mcg/24 h
13-17 years: 4.0-56 mcg/24 h
≥18 years: 3.5-45 mcg/24 h
Use the factor below to convert from mcg/24 hr to nmol/24 hr:
Conversion factor
Cortisol: mcg/24 h x 2.76=nmol/24 hr (molecular weight=362.5)
For International System of Units (SI) conversion for Reference Values, see www.mayocliniclabs.com/order-tests/si-unit-conversion.html.
Useful For
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.
CPT Code Information
82530
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CORTU | Cortisol, Free, U | 43126-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 8546 | Cortisol, U | 14158-0 |
| TM93 | Collection Duration (h) | 13362-9 |
| VL47 | Volume (mL) | 3167-4 |
Supportive Data
In Mayo's reference value study, gender was found to significantly influence cortisol values (P value=0.001). However, while this was statistically significant, gender explained only 6% of the variability in cortisol normal ranges and, therefore, was not considered to have a clinically significant impact on cortisol reference values.