Cortisol, Free and Total, Serum
Use
The test is useful for assessing cortisol status, especially in cases where there may be abnormalities in cortisol-binding proteins or albumin. It is also helpful for evaluating adrenal function in critically ill or stressed patients, which can help prevent unnecessary glucocorticoid therapy. Additionally, this test can be used as a second-order confirmation when initial cortisol measurements by immunoassay are inconsistent with clinical symptoms or when patients are suspected of using synthetic steroids. It is an adjunct in differentiating primary and secondary adrenal insufficiency and in diagnosing Cushing syndrome.
Special Instructions
Morning samples are preferred, specifically those collected between 6 a.m. and 10:30 a.m., with specimen retention time being 14 days. Special attention should be given to collection times, which need to be recorded in military time. Specimens should be collected in a red top tube and transferred to a plastic vial as indicated. Serum gel tubes are not acceptable.
Limitations
The test might not be suitable for evaluating cortisol responses to metyrapone. It is not recommended for evaluating low plasma cortisol specifically for congenital adrenal hyperplasia. Cross-reactivity or increased results can occur with exogenous estrogens and certain drugs. Acute stress, alcoholism, and various drugs can affect results and diurnal variation.
New York Approved
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
LOINC Codes
- 100662-6
- 2143-6
- 9813-7
- 9812-9
- 2145-1
Result Turnaround Time
3-11 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1.85 mL
Minimum Volume
1 mL
Container
Plastic vial
Collection Instructions
Collect in red top tube, centrifuge and aliquot serum into a plastic vial. Preferred to collect morning specimens between 6 a.m. and 10:30 a.m.
Patient Preparation
Preferred collection time is between 6 a.m. and 10:30 a.m., with morning samples being ideal.
Causes for Rejection
Gross hemolysis, gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 28 days |
| Refrigerated | 28 days |
| Frozen | 28 days |