Test Details
Methodology
Electrochemiluminescence immunoassay (ECLIA)
Result Turnaround Time
1 - 2 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
Evaluation of possible primary and secondary adrenal insufficiency.1-3,5
Special Instructions
Draw blood for baseline cortisol. Inject cosyntropin 250 μg IM or IV (if IV, dilute cosyntropin in 2-5 mL of sterile saline and inject over two minutes). Draw blood for stimulated cortisol 60 minutes after.1-3
Treatment for patients in suspected adrenal crisis should not be delayed while waiting for the results of ACTH (cosyntropin) stimulation testing.3,4 Formal confirmation of diagnosis can be carried out after clinical recovery.
Limitations
Pregnancy, contraceptives, and estrogen therapy can give rise to elevated cortisol concentrations. In samples from patients who have been treated with prednisolone,methylprednisolone, or prednisone, falsely elevated concentrations of cortisol may be determined due to cross-reactivity.6 Patients suffering from 21-hydroxylase-deficiency exhibit elevated 21-deoxycortisol levels, and this can also give rise to elevated cortisol levels.6 Severe stress can also give rise to elevated cortisol concentrations.6
As with all tests containing monoclonal antibodies, erroneous findings may be obtained from patients who have been treated with monoclonal mouse antibodies or who have received them for diagnostic purposes. In rare cases, interference due to extremely high titers of antibodies to streptavidin and ruthenium can occur. The test contains additives, which minimize these effects.
Custom Additional Information
The ACTH stimulation test (Cosyntropin) is used to assist in diagnosing primary and secondary adrenal insufficiency. Cosyntropin (ACTH 1-24) consists of the first 24 amino acids of the N-terminal portion of the intact native ACTH molecule (ACTH 1-36). It is the biologically active region of intact ACTH and is less allergenic than other forms of ACTH.7,8 It acts rapidly when bound to the melanocortin-2 receptor (MC2R) of the adrenal cortex initiating synthesis and release of cortisol and its precursors. The magnitude and duration of response as measured by serum steroid levels may depend on the prior stimulation or suppression of the hypothalamic-pituitary-adrenal axis and the adequacy of drug administration.
Interpretation: A normal response is a rise from the baseline of cortisol, reaching at least 14.5 μg/dL 30 or 60-minutes post stimulation.9 A blunted or absent response suggests some level of adrenal insufficiency, cortical atrophy or significant suppression. Results should be interpreted within the context of patient’s medical history and clinical symptoms, particularly for patients with results near the cutoff.
Specimen Requirements
Specimen
Serum
Volume
1.0 mL (each specimen)
Minimum Volume
0.7 mL (each specimen). (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection Instructions
If tube other than a gel-barrier tube is used, transfer separated serum to a plastic transport tube. Note: Label each tube with the patient's name, collection time, and date. Submit specimens simultaneously on the same test request form.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Storage Instructions
Room temperature
Causes for Rejection
Plasma specimen
Footnotes
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 140761 | Cortisol, ACTH Stimulation | 34541-3 | 140792 | Cortisol Baseline | ug/dL | 43215-3 |
| 140761 | Cortisol, ACTH Stimulation | 34541-3 | 140793 | Cortisol Stimulated | ug/dL | 34476-2 |
| Order Code | 140761 | |||||
| Order Code Name | Cortisol, ACTH Stimulation | |||||
| Order Loinc | 34541-3 | |||||
| Result Code | 140792 | |||||
| Result Code Name | Cortisol Baseline | |||||
| UofM | ug/dL | |||||
| Result LOINC | 43215-3 | |||||
| Order Code | 140761 | |||||
| Order Code Name | Cortisol, ACTH Stimulation | |||||
| Order Loinc | 34541-3 | |||||
| Result Code | 140793 | |||||
| Result Code Name | Cortisol Stimulated | |||||
| UofM | ug/dL | |||||
| Result LOINC | 34476-2 |