Endocrinology• Updated 21 October 2026

Cortisol Test

A blood test that measures cortisol, a stress hormone made by the adrenal glands.

Results: Usually within a day Specimen: Blood

Quick Summary

Primary Purpose

To check for too much or too little cortisol (Cushing's syndrome or adrenal insufficiency).

What It Measures

Cortisol level, often in the morning, sometimes with stimulation or suppression tests.

Preparation

Usually an early-morning sample; follow instructions about steroid medicines.

Overview

Cortisol is highest in the morning and lowest at night.

Steroid medicines affect results.

What It Measures

Cortisol

Blood level.

How It's Performed

  1. 01

    Preparation

    Usually no special preparation. Tell the staff about medicines you take.

  2. 02

    Blood sample

    A small amount of blood is taken from a vein in your arm with a thin needle.

  3. 03

    Afterwards

    Press on the spot for a minute. A small bruise is common; you can go back to normal activities.

Reference Ranges

Note: Normal ranges vary by laboratory. Consult your report for the specific reference used.

ParameterTypical Range (Adult)Units
Morning cortisol5–25µg/dL

Interpreting Results & Next Steps

Discuss with Doctor

Normal ranges differ between laboratories, ages and sexes; always use the range printed on your report and ask your doctor what your results mean.

If values are Low:

Low morning cortisol may suggest adrenal insufficiency.

If values are High:

High cortisol may suggest Cushing's syndrome, stress or steroid use.

Sources and further reading

Last updated 21 October 2026. For more detail, see these trusted health organisations.