Cortisol, Serum
Use
This test is useful for the discrimination between primary and secondary adrenal insufficiency and assists in the differential diagnosis of Cushing syndrome. It measures serum cortisol levels, which play a crucial role in glucose metabolism and the body's stress response. Cortisol is primarily regulated by corticotropin from the pituitary gland. Hypercortisolism and hypocortisolism both have distinct causes which this test can help identify. It is not recommended for evaluating response to metyrapone.
Special Instructions
Morning (8 a.m.) and afternoon (4 p.m.) specimens are preferred. Centrifuge the specimen within 2 hours of collection. For red-top tubes, aliquot serum into a plastic vial after centrifugation. Include collection time with the specimen. If multiple specimens are collected, send separate orders for each.
Limitations
Acute stress, alcoholism, depression, and some medications can affect cortisol levels. Falsely increased cortisol levels may be seen in patients taking prednisone or those with cross-reactivity issues due to antibodies like HAMA. A low plasma cortisol level doesn't conclusively indicate congenital adrenal hyperplasia. Results can also be affected by exogenous estrogens during pregnancy, and secondary adrenal insufficiency may present false normal responses in some tests.
FDA ApprovedNew York Approved
Methodology
Immunoassay (ELISA)
Biomarkers
LOINC Codes
- 87429-7
- 83088-5
- 9813-7
- 9812-9
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
0.6 mL
Minimum Volume
0.5 mL
Container
Serum gel; Acceptable: Red top; Submit in Plastic vial
Collection Instructions
Morning (8 a.m.) and afternoon (4 p.m.) preferred; centrifuge within 2 hours; aliquot serum into plastic vial for red-top tubes; include time of collection.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 14 days |
| Frozen | 90 days |