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Test ID CORTF Cortisol, Free, Serum

Additional Testing Requirements


Necessary Information

Include time of collection.

Specimen Required

Collection Container/Tube: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1.25 mL

Collection Instructions:

1. Morning (8 a.m.) specimens are preferred. The 8 a.m. cortisol can be referred to as the a.m. cortisol and can be collected any time between 6 a.m. and 10:30 a.m. in the morning.

2. Centrifuge and aliquot serum into a plastic vial.

Additional Information: If multiple specimens are collected, send a separate order for each specimen.

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

Method Name

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

Reporting Name

Cortisol, Free, S

Specimen Type

Serum Red

Specimen Minimum Volume

1 mL

Specimen Stability Information

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

Reference Values

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

Day(s) Performed

Tuesday, Thursday, Friday

Report Available

4 to 7 days

Performing Laboratory

Mayo Clinic 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 US 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