Cortisol blood test
In short
A typical adult cortisol result is 7 to 25 µg/dL (morning (about 8 am)) and 2 to 14 µg/dL (afternoon (about 4 pm)). A high cortisol most often comes from stress, illness, estrogen or steroid medicines, not an adrenal problem. One blood test is not enough to show Cushing's syndrome, a rare condition of too much cortisol. Always read your result against the range printed on your own report.
The main stress hormone, made by the adrenal glands above the kidneys.
Cortisol helps control blood sugar, blood pressure and the body's response to stress. It follows a daily rhythm: highest soon after waking, much lower by the afternoon, and lowest late at night. So the time of the blood draw matters when reading the number.
Is my Cortisol high or low?
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Typical range
| For | Range | Unit |
|---|---|---|
| Adults · morning (about 8 am) | 7–25 | µg/dL |
| Adults · afternoon (about 4 pm) | 2–14 | µg/dL |
| Adults · morning (about 8 am) | 193–690 | nmol/L |
| Adults · afternoon (about 4 pm) | 55–386 | nmol/L |
Typical ranges for adults. Labs differ a little, so the range printed next to your result is the one to go by.
If your Cortisol is high
A high cortisol most often comes from stress, illness, estrogen or steroid medicines, not an adrenal problem. One blood test is not enough to show Cushing's syndrome, a rare condition of too much cortisol.
Common reasons
- Stress, pain or a hard workout before the test
- A recent illness, surgery or hospital stay
- Birth control pills or hormone therapy containing estrogen
- Some steroid medicines, which some tests read as cortisol
- Pregnancy, which raises cortisol naturally
- Heavy drinking or depression
- Less often: Cushing's syndrome, from an adrenal or pituitary (brain gland) growth
If your Cortisol is low
A low cortisol is common when blood is drawn later in the day, as levels naturally fall. A truly low morning level can be a sign the adrenal glands are not making enough.
Common reasons
- Blood drawn in the afternoon or evening, when cortisol is naturally lower
- Steroid medicines, including inhalers, creams and joint shots, which quiet the adrenals
- Recently stopping steroid medicines after taking them for a long time
- Less often: adrenal damage (Addison's disease) or a pituitary (brain gland) problem
What can throw it off
The time of day matters most, and stress, estrogen, steroid medicines and pregnancy can all move cortisol.
Questions to take to your appointment
- 1Does the time of my blood draw change how you read this?
- 2Could my steroid medicines, inhalers or birth control pills explain it?
- 3Do I need a different cortisol test, such as saliva or urine?
Read together with
Doctors rarely read Cortisol alone. These usually sit next to it.
Quick answers
What is the cortisol blood test?
Cortisol: The main stress hormone, made by the adrenal glands above the kidneys. Cortisol helps control blood sugar, blood pressure and the body's response to stress. It follows a daily rhythm: highest soon after waking, much lower by the afternoon, and lowest late at night. So the time of the blood draw matters when reading the number.
What is a normal cortisol level?
For most adults, cortisol is typically 7 to 25 µg/dL (morning (about 8 am)) and 2 to 14 µg/dL (afternoon (about 4 pm)). Some countries print it in nmol/L, so check the unit first. Labs differ a little, so the range printed next to your result is the one to go by.
What does a high cortisol mean?
A high cortisol most often comes from stress, illness, estrogen or steroid medicines, not an adrenal problem. One blood test is not enough to show Cushing's syndrome, a rare condition of too much cortisol. Common reasons include stress, pain or a hard workout before the test; a recent illness, surgery or hospital stay; birth control pills or hormone therapy containing estrogen; and some steroid medicines, which some tests read as cortisol. A doctor reads it together with your other results and how you feel.
What does a low cortisol mean?
A low cortisol is common when blood is drawn later in the day, as levels naturally fall. A truly low morning level can be a sign the adrenal glands are not making enough. Common reasons include blood drawn in the afternoon or evening, when cortisol is naturally lower; steroid medicines, including inhalers, creams and joint shots, which quiet the adrenals; recently stopping steroid medicines after taking them for a long time; and less often: adrenal damage (Addison's disease) or a pituitary (brain gland) problem.
What can affect my cortisol result?
The time of day matters most, and stress, estrogen, steroid medicines and pregnancy can all move cortisol.
What should I ask my doctor about my cortisol?
Questions worth taking to the appointment: Does the time of my blood draw change how you read this? Could my steroid medicines, inhalers or birth control pills explain it? Do I need a different cortisol test, such as saliva or urine?
What this page can’t do
It reads each number on its own.
Doctors read results together — ALT with AST, ferritin with hemoglobin, TSH with free T4. A pattern says more than any single flag.
It doesn't know you.
Your age, your medicines, how you feel and your last result all change what a number means.
It doesn't remember.
Close this page and your results are gone. That's on purpose: nothing was ever sent to us.
We also make Vita: Health Coach, an app for those parts. It reads your whole report with your medicines and history in mind, answers follow-up questions in plain words, and keeps your reports in one place — for you and for the people you look after.
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