How to Test Cortisol Levels

A blood draw, usually done in the morning when cortisol should be near its peak, measures your total cortisol at that single moment. It's the standard starting point in medical settings and is often used when a provider is screening for conditions involving very high or very low cortisol. Its limitation is timing: one snapshot can't show your daily rhythm, and the stress of a blood draw itself can nudge the number.

Saliva testing measures free cortisol — the active portion — and because collection is easy, it's typically done at multiple points across one day: shortly after waking, midday, evening, and bedtime. Plotted together, these points show your cortisol curve, which is often more informative than any single value. Most at-home cortisol kits use this method. Typical guidance is to avoid eating, drinking anything besides water, or brushing your teeth for a period before each sample — always follow the exact instructions included with your specific kit.

Urine panels — including dried-urine formats collected several times across a day — measure cortisol along with its metabolites, which reflect how your body is producing and processing the hormone over time. Practitioners often use these panels when they want a fuller hormonal picture rather than a single marker.

If a medical condition is suspected, start with your doctor — they'll order the appropriate testing and interpret it in context. If you're exploring your daily rhythm out of general health interest, a multi-point saliva or urine panel gives the most complete view. Whatever you choose, consistency matters: test on a typical day, note your sleep and stress, and review results with a qualified provider.