Cortisol Blood Testing Fact Sheet

Overview of the Test

Cortisol is released by the adrenal glands and plays an important role in metabolizing carbohydrates, proteins and lipids. It is also a key stress-response hormone. During times of stress, cortisol mobilizes biological resources to repair and protect the body. However, as we age, our bodies continue to produce higher levels of cortisol for longer, which means that stress becomes even more damaging.

The blood cortisol test measures serum cortisol (hydrocortisone) and is able to diagnose conditions such as Cushing’s syndrome that is associated with too much cortisol. Higher levels of cortisol are also linked with many other health conditions, including hypertension (high blood pressure), heart disease, high blood sugar levels (and diabetes), osteoporosis, obesity and Alzheimer’s disease. Cortisol levels can also be measured from salivary or urinary samples.

Evidence and Science behind the Test

Generally, cortisol levels are at their highest upon waking and at their lowest at bedtime (although with shift workers this pattern can change). Normal morning ranges are 6 – 23 micrograms per deciliter (ug/dL). A higher level of cortisol in the morning, or a level that does not drop during the afternoon or evening means that there is probably an overproduction of cortisol.

How is it done?

If you are taking certain medications such as estrogen, you may need to stop taking it during the test, as it may affect results. You may also need to fast the night before. A blood sample from the arm is usually taken at around eight in the morning and around four in the afternoon.

Who does it?

Doctors, nurses and other qualified professionals.


With insurance, it can be free, or up to 50% cost with coinsurance. Those without insurance may pay a minimum of around $50 and as much as $150 upwards, depending on how frequently the blood test is required.

When and How Often?

There are no set guidelines as such for cortisol blood tests, although those who suffer with specific conditions such as Addison’s or Cushing’s will often undergo regular cortisol testing.


A cortisol blood test can be affected by many factors including emotional stress, physical stress, illness, pregnancy and medications. Because the blood test is so sensitive to stress, a number of samples may be necessary, or the doctor may use other cortisol tests, such as those requiring salivary or urine samples to help make an accurate assessment about cortisol levels. Doctors may also need to carry out additional tests, such as a dexamethasone suppression test, which will assess how the adrenal glands respond to the hormone ACTH (which regulates cortisol). Researchers have also shown that professionals should exercise caution when making conclusions about adrenal gland function based on a single random blood cortisol test.


Last reviewed 26/Feb/2014


Related Posts

The following two tabs change content below.
Whilst wielding a couple of dumbbells in a gym class in 2003, Kate experienced an epiphany around the lack of accepted best practice guidelines when it came to staying well and avoiding disease. Kate realized that she had no chance of slowing her own aging process unless she became better educated about her options.

Latest posts by Kate Marie (see all)