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Test Code CORTF Cortisol, Free, Serum

Additional Testing Requirements

If multiple specimens are drawn, send separate order for each specimen.

Necessary Information

Include time of draw.

Specimen Required

Container/Tube: Red top

Preferred: Red top

Specimen Volume: 1.25 mL

Collection Instructions: Morning (8 a.m.) specimens are preferred. The 8 a.m. cortisol can be referred to as the a.m. cortisol and can be drawn anywhere between 6 a.m. and 10:30 a.m. in the morning.

Useful For

Assessment of cortisol status in cases where there is known or a suspected abnormality in cortisol-binding proteins or albumin


Assessment of adrenal function in the critically ill or stressed patient, thus preventing unnecessary use of glucocorticoid therapy

Special Instructions

Method Name

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

Reporting Name

Cortisol, Free, S

Specimen Type

Serum Red

Specimen Minimum Volume

0.75 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Red Refrigerated (preferred) 28 days
  Ambient  28 days
  Frozen  28 days

Reject Due To


Mild OK; Gross reject


Mild OK; Gross OK


Mild OK; Gross reject



Reference Values

6-10:30 a.m. Collection: 0.121-1.065 mcg/dL

Day(s) and Time(s) Performed


Analytic Time

2 days

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


LOINC Code Information

Test ID Test Order Name Order LOINC Value
CORTF Cortisol, Free, S 2145-1


Result ID Test Result Name Result LOINC Value
65423 Cortisol, Free, S 2145-1