Hormones
Cortisol (Morning) — what it measures
For understanding, not diagnosis. Reference ranges differ between laboratories; the ranges on your own report, and your doctor’s reading of them, always come first.
What it measures
Cortisol is the adrenal hormone that helps regulate energy, blood pressure and the stress response, following a daily rhythm that peaks in the early morning. A morning blood cortisol is often the first step when adrenal function is being assessed.
What can skew it
Time of day is critical — an afternoon value cannot be compared with morning ranges. Stress, illness, poor sleep and steroid medicines also move results.
Reference ranges
Reference ranges vary by laboratory, assay and sampling time, so cortisol results should only be interpreted by your clinician with the timing recorded.
Medical disclaimer: This page is educational only. It cannot tell you whether your result is normal or what to do about it — that is a decision for your doctor, with your full history.