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Test Code Billings Clinic: 4061 Cortisol, Plasma or Serum

Important Note

Circulating cortisol results from patients receiving Prednisolone or Prednisone therapy may be falsely elevated. Exercise caution with cortisol determinations for patients undergoing therapy with these and structurally related synthetic corticosteroids.

 

The performance of the assay has not been established with neonatal specimens.

Additional Codes

If cortisol is being ordered as part of an adrenocorticotropic hormone (ACTH) stimulation test, order Billings Clinic: #4186 “Cortisol, Pre-Cosyntropin, Plasma or Serum” and Billings Clinic: #4187 “Cortisol, Post-Cosyntropin, Plasma or Serum.”

Performing Laboratory

Billings Clinic Laboratory: Chemistry

Useful For

  • Discrimination between primary and secondary adrenal insufficiency
  • Differential diagnosis of Cushing syndrome

Methodology

Chemiluminescent Immunoassay

Specimen Requirements

Submit only 1 of the following specimens:

Serum or plasma should be physically separated from cells as soon as possible with a maximum limit of two hours from the time of collection.

 

Plasma

  • Indicate time of draw on request form.
  • Label specimen appropriately (plasma).
  • If multiple (morning and afternoon) specimens are drawn, send separate request form for each specimen.
  • Draw blood in a green-top (lithium heparin) tube(s) (early morning [8 a.m.] draw is preferred).
  • Spin down and send 1 mL of plasma frozen in plastic vial.

 

Serum

  • Indicate time of draw on request form.
  • Label specimen appropriately (serum).
  • If multiple (morning and afternoon) specimens are drawn, send separate request form for each specimen.
  • Draw blood in a plain, red-top tube(s) or a serum gel tube(s) (early morning [8 a.m.] draw is preferred).
  • Spin down and send 1 mL of serum frozen in plastic vial.

Storage/Stability

Specimen Type Temperature Time
Plasma, Serum Refrigerated 2 days
  Frozen (preferred) 1 month
  Ambient 8 hours

 

Reject Due To

  • Samples stored at room temperature greater than 8 hours
  • Samples frozen and thawed more than once
  • Gross hemolysis

Reference Values

3.09 - 22.40 µg/dL

 

AM        5.27 - 22.45 ug/dL

PM        3.44 - 16.76 ug/dL

Day(s) Test Set Up

Daily

Test Classification and CPT Coding

82533 - Cortisol; total

LOINC Code Information

Reporting Name LOINC Code
Cortisol 2143-6