What does the Salivary Free Cortisol (Single Timepoint) test measure?

Why is Salivary Free Cortisol (Single Timepoint) measured?

An extra cortisol timepoint increases the sensitivity of diurnal rhythm assessment, particularly when practitioners suspect a subtle phase shift, a mid-afternoon nadir that is too high or too low, or need to document cortisol kinetics around a symptom window. It is ordered as an add-on to a baseline diurnal panel rather than as a standalone test, since a single isolated value has limited interpretive power without the rest of the curve.

Reference ranges

Standard reference

Time-dependent; varies by collection interval and proprietary DUTCH reference data.

Functional medicine optimal

Optimal ranges are context-dependent: waking cortisol should be robust, mid-morning values should show a sharp decline, and evening samples should reach a physiological nadir. An extra timepoint is judged by whether it fits the expected trajectory or reveals a dysregulated segment.

Units

ng/mL, nmol/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.