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Cortisol is a hormone made by your adrenal glands, two small glands that sit on top of your kidneys. A level that is too high or too low can point to a problem with your adrenal glands or with your pituitary gland, a gland in your brain.[1]
On this page you can read what cortisol is, what the guidelines say about a level that is too low or too high, what affects your level and which other levels are best read alongside it.
Also known as: blood cortisol, plasma cortisol, serum cortisol, free cortisol, stress hormone. At the lab: CORT.
Cortisol is a hormone. Hormones are messengers in your blood that control how certain cells or organs work. Cortisol acts in almost every organ and tissue in your body.[1]
Your adrenal glands make cortisol. Your pituitary gland makes another hormone, ACTH, which tells your adrenal glands how much cortisol to make.[1]
Most cortisol is in your blood. That is why it is often measured in blood taken from a vein in your arm. Some of it also ends up in your urine and saliva.[1]
Cortisol helps your body deal with stress, keep inflammation in check, run your metabolism and manage your blood pressure. A level that is too high or too low can be very serious.[1]
A guideline from the Endocrine Society recommends testing anyone with symptoms or signs that point to adrenal glands that are not making enough. For people who are acutely ill or at higher risk, the guideline advises testing quickly.[2]
The same guideline says this also applies to people who are pregnant and have ongoing nausea, tiredness and low blood pressure with no clear cause.[2]
Labplusarts, the lab BioProfile works with, uses a range of 70 to 500 nmol/l for cortisol. The lab calls a level between these limits normal.[3]
| Value | What it can mean | Who it is for |
|---|---|---|
| 70 to 500 nmol/l[3] | The lab calls this value normal | Cortisol in blood, measured by Labplusarts |
Source: Labplusarts, the lab BioProfile works with. Reference range for cortisol in blood (CORT).[3]
A value that is too low can point to adrenal glands that are not making enough cortisol, or to a pituitary gland that is making too little ACTH. Suddenly stopping certain steroid medicines can also give a low value. With too little cortisol, you can feel tired for a long time, have weak muscles, have less appetite and have abdominal pain, and your weight can drop.[1]
A high level can point to a problem with your adrenal glands or your pituitary gland, or to long-term use of high doses of certain steroid medicines, such as prednisone. With too much cortisol, you may gain weight, get thin arms and legs, get a rounder face, bruise easily, get wide purple stretch marks on your skin and have weak muscles.[1]
BioProfile is working on its own zones for each value, from risk to optimal. A doctor reviews those zones before they appear in your result.
Your cortisol goes up and down over the day. It is usually highest in the morning and much lower in the afternoon. That is why blood is sometimes taken twice in one day.[1]
Stress and exercise can raise your cortisol. That is why you may need to rest before your blood is taken.[1]
Long-term use of high doses of certain steroid medicines can raise your cortisol. Tell your doctor which medicines you use, including skin creams. Never stop a medicine without talking to your doctor first.[1]
Your pituitary gland uses ACTH to control how much cortisol your adrenal glands make. If either gland is not working as well as it should, your cortisol can change.[1]
Cortisol is included in BioProfile 121 and 150.[4]
The BioProfile editorial team wrote this page on 10 October 2026 from the sources below, which we read on 10 October 2026. Every number on this page appears in one of those sources, with that source's number next to it. An expert has yet to check this page; after that check, the expert's name and the date of the check will appear at the top. This page offers explanation, not a diagnosis. Discuss a value outside the range with your GP.
