---
title: "Morning 8:00 AM Fasting Serum Cortisol Optimal Range vs Lab Normal (2026 Clinical Decoder & Protocol) | Nutrition Research Labs"
source_url: "https://nutritionresearchlabs.com/biomarkers/cortisol-am"
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description: "Decode your Morning 8:00 AM Fasting Serum Cortisol (Morning Cortisol) blood test: Longevity Optimal Target (10.0–15.0 mcg/dL) vs Standard Lab Normal (6.0–23.0 mcg/dL), assay interference, and Grade-A clinical protocols."
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> **Canonical Source:** [https://nutritionresearchlabs.com/biomarkers/cortisol-am](https://nutritionresearchlabs.com/biomarkers/cortisol-am)
>
> *Decode your Morning 8:00 AM Fasting Serum Cortisol (Morning Cortisol) blood test: Longevity Optimal Target (10.0–15.0 mcg/dL) vs Standard Lab Normal (6.0–23.0 mcg/dL), assay interference, and Grade-A clinical protocols.*

## Reference Range Comparison (mcg/dL)

- **Longevity & Metabolic Optimal Range:** 10.0 – 15.0 mcg/dL
- **Standard Lab Reference Interval ("Normal"):** 6.0 – 23.0 mcg/dL
- **Why Standard Lab Ranges Mislead Patients:** The typical laboratory morning range (6.0 to 23.0 mcg/dL) is vast. A reading of 22 mcg/dL at 8:00 AM in a chronically stressed individual will be labeled
- **Pre-Draw Supplement Assay Interference Warning:** Phlebotomy must occur within 30 to 60 minutes of waking (ideally 8:00 AM). Cortisol drops rapidly by midday. Acute sleep deprivation, panic, or taking oral hydrocortisone/prednisone invalidates endogenous readings.

## Decode the Next Biomarker on Your Blood Panel

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