For serum cortisol, Vibrant reference ranges are validated for two different time windows:
- AM window: Specifically 6-10am (reference range 6.2 – 19.4 µg/dL)
- PM window: Specifically 4-8pm (reference range 2.3 – 11.9 µg/dL)
Depending on what time of day the sample is collected, either the AM or PM reference ranges will be applied.