Overview: Cortisol Evening TestIntroduction: The Cortisol Evening Test measures evening cortisol to diagnose adrenal disorders, causing fatigue, weight gain, or sleep issues. Aligned with 2023 AACE guidelines, it uses an immunoassay for high sensitivity, aiding in endocrine screening. This test is critical for guiding diagnosis, treatment, and improving outcomes in endocrinology for patients with suspected adrenal dysfunction.
Other Names: Evening Cortisol Assay, Adrenal Function Test.
FDA Status: Laboratory-developed test (LDT), meeting endocrinology standards for diagnostic accuracy.
Historical Milestone: Cortisol testing began in the 1960s with adrenal research. Evening cortisol assays emerged in the 1980s, and by the 2000s, high-sensitivity immunoassays improved accuracy.
Purpose: Diagnoses adrenal disorders like Cushing's syndrome, guides treatment, and monitors evening cortisol levels in patients with fatigue or sleep issues.
Test Parameters: 1. Cortisol
Pretest Condition: Fasting for 10-12 hours required to stabilize cortisol levels. Collect serum, plasma, or saliva in the evening. Report symptoms like fatigue or sleep issues, and list medications like steroids.
Specimen: 2-5 mL serum (SST), 2-4 mL plasma (EDTA), or 1-2 mL saliva (sterile container). Centrifuge serum/plasma within 1 hour. Transport in a biohazard bag within 8 hours.
Sample Stability at Room Temperature: 8 hours
Sample Stability at Refrigeration: 7 days
Sample Stability at Frozen: 6 months
Medical History: Document fatigue, sleep issues, or history of adrenal disorders. Include current medications, especially steroids or hormone therapies.
Consent: Written consent required, detailing the tests purpose, diagnostic implications, and potential need for adrenal therapy.
Procedural Considerations: Uses an immunoassay to measure evening cortisol levels. Results are available in 1-2 days, enabling rapid clinical decisions.
Factors Affecting Result Accuracy: Non-fasting samples, stress, or improper collection timing may alter results. Hemolysis can degrade samples.
Clinical Significance: Elevated evening cortisol levels indicate Cushing's syndrome, prompting therapy. Low levels suggest adrenal insufficiency.
Specialist Consultation: Consult an endocrinologist for result interpretation. A sleep specialist referral is advised for sleep-related issues.
Additional Supporting Tests: ACTH test, morning cortisol test, or adrenal imaging to confirm adrenal disorders.
Test Limitations: Results may be affected by stress or improper timing. Clinical correlation is required.
References: AACE Adrenal Guidelines, 2023; Journal of Clinical Endocrinology, Nieman LK, 2022.
