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Test Code Billings Clinic: 4187 Cortisol, Post-Cosyntropin, 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.

Performing Laboratory

Billings Clinic Laboratory: Chemistry

Useful For

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

Methodology

Chemiluminescence 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

  • Draw blood in a green-top (lithium heparin) tube(s).
  • Spin down and send 1.0 mL of plasma frozen
  • Indicate time of draw on request form.
  • Label specimen appropriately (plasma).
  • If there is more than 1 post specimen, note the time of post-injection on the request form and on the vial.

 

Serum

  • Draw blood in a plain, red-top tube(s) or a serum gel tube(s).
  • Spin down and send 1.0 mL of serum frozen
  • Indicate time of draw on request form.
  • Label specimen appropriately (serum).
  • If there is more than 1 post specimen, note the time of post-injection on the request form and on the 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

Varies

Day(s) Test Set Up

Daily

Test Classification and CPT Coding

80400 - ACTH stimualtion panel; for adrenal insufficiency

LOINC Code Information

Reporting Name LOINC Code
Cortisol, Post ACTH 2143-6

 

Physician Office Specimen Requirements Additional Information

This test should be ordered for the second specimen of an adrenocorticotropic hormone (ACTH) stimulation test (ie, 1 hour after the ACTH dose). Order Billings Clinic: #4186 “Cortisol, Pre-Cosyntropin, Plasma or Serum” for the first specimen of a stimulation test.