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Test Code CORTAM Cortisol AM, LAB2382


Chemiluminescence/Competitive Binding Immunoenzymatic Assay

Performing Laboratory

St. Luke's Hospital Cedar Rapids

Specimen Requirements


Preferred: Green-top (lithium heparin) tube

Acceptable: Gold-top serum gel tube or Plain Red-top tube

Specimen Volume: 170 uL of plasma or serum

Stability: Keep tubes stoppered and upright at all times.  Do not use samples that have been stored at room temperature for longer than 8 hours.  Tightly cap and refrigerate specimens at 2° to 8°C if the assay is not completed within 8 hours.  Freeze samples at or below -20°C if the sample is not assayed within 48 hours.  Freeze samples only once and mix thoroughly after thawing. 

Collection Instructions:

Note: 1. Human anti-mouse antibodies or other heterophile antibodies may be present in patient specimens. This assay has been specially formulated to minimize the effects of these antibodies, however results from patients known to have these antibodies should be carefully evaluated.

2. Label specimen appropriately (plasma /serum).

Reference Values

AM: 4.3-22.4 ug/dL


In normal patients, serum cortisol levels fall in late afternoon to approximately one-half the morning values.

Sample should be collected in the AM.  If afternoon, CORTPM should be used.

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding


Useful For

Cortisol levels are useful in the diagnosis of hypothalamic, pituitary, or adrenal malfunction. 

Excess cortisol levels are found in Cushing’s syndrome (adrenal cortical hyperfunction) while decreased levels are found in Addison’s Disease (adrenal cortical insufficiency).