Lab Test

Cortisol, Free, Urine, Random

Free Cortisol, Random Urine, Random Urine Cortisol

Test Codes



Send Outs


This test is useful for investigating suspected hypercortisolism when a 24 hour urine collection is prohibitive (i.e., pediatric patients).

NOTE: Urine Creatinine test is performed on each sample.

Specimen Collection Criteria

Collect: Random urine specimen in a screw-capped container (preferred) or other sterile collection container with no preservative.

Physician Office/Draw Specimen Preparation

Maintain specimen refrigerated (2-8°C or 36-46°F) prior to transport.

Preparation for Courier Transport

Transport: 10.0 mL urine, refrigerated (2-8°C or 36-46°F). (Minimum: 4.0 mL)

Rejection Criteria

  • Specimens not collected and processed as indicated.

In-Lab Processing

Maintain specimen refrigerated (2-8°C or 36-46°F) prior to transport.

Transport: 10.0 mL urine, refrigerated (2-8°C or 36-46°F). (Minimum: 4.0 mL)


Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 7 days
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): 28 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Sendout Laboratory with any questions.


Sent to Mayo Medical Laboratory, Rochester, MN.


Monday – Friday.
Results available in 3-6 days.

Reference Range

By report.

Test Methodology

Enzymatic Colorimetric Assay/Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS).

Clinical Utility

  • Cortisol is a steroid hormone synthesized from cholesterol by a multienzyme cascade in the adrenal glands. It is the main glucocorticoid in humans and acts as a gene transcription factor influencing a multitude of cellular responses in virtually all tissues. It plays critical role in glucose metabolism, maintenance of vascular tone, immune response regulation, and in the body's response to stress. Its production is under hypothalamic-pituitary feedback control.
  • Only a small percentage of circulating cortisol is biologically active (free), with the majority of cortisol inactive (protein bound). As plasma cortisol values increase, free cortisol (i.e., unconjugated cortisol or hydrocortisone) increases and is filtered through the glomerulus. Urinary free cortisol (UFC) correlates well with the concentration of plasma free cortisol. UFC represents excretion of the circulating, biologically active, free cortisol that is responsible for the signs and symptoms of hypercortisolism. UFC is a sensitive test for the various types of adrenocortical dysfunction, particularly hypercortisolism (Cushing's syndrome). A measurement of 24-hour UFC excretion is the preferred screening test for Cushing syndrome.

CPT Codes

LOINC:  34909-2


Last Updated


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