There are variety of cortisol tests on offer and it's very confusing to know what to order. We clarify different types to help you decide what may fit your needs.
Cortisol levels rise as soon as we wake up and then drop throughout the day.
If you feel sleepy at wrong times, are stressed or find it difficult to fall asleep at night, your HPA axis might be of and cause a cortisol imbalance.
The HPA axis involves three components: Hypothalamus and Pituitary in the brain, and Adrenal glands on the kidneys.
A cortisol test can help check where the problem lies. But do you know which test to order?
Because cortisol hormone levels change through out the day, it's important to understand the daily trend before making a decision.
Figure 1: The daily trend of cortisol hormone levels, with a prominent morning peak and continuous drop in the afternoon and at night.
In general, there are two main things to decide when you want to order a cortisol test:
Type of sample - blood or saliva or urine
Number of samples collected - one, two, four or more
Below we discuss each of them in detail.
The cortisol blood tests are common. Most likely that's what your doctor will order for you.
This is also the type you get in a hospital or with some of the bigger labs (Quest, Labcorp, etc.). A blood test checks for the total cortisol levels - both free and bound forms.
However, it is challenging to collect many samples, and a nurse or phlebotomist needs to draw the blood with a needle. But some people might find this process difficult, especially children (because of fear of needles) and seniors (as veins become thinner with age).
A cortisol saliva test is equally reliable but more patient friendly. One can collect many samples, right from their home.
However, cortisol saliva tests are not common because your doctor might not know about them, or doesn't understand them fully to interpret the results. You should have a conversation to nudge them for such a friendly method, since they are becoming more common and popular.
A cortisol test checks the free cortisol levels, released through the saliva glands.
A cortisol urine test checks the metabolites of cortisol (chemicals formed from the break down of cortisol by the body).
Multiple urine samples can be collected at different hours and mailed to the lab. Therefore, urine cortisol tests are also patient friendly, but they don't seem to be as common as saliva tests.
If you were to collect only one sample, it should be to check the morning cortisol levels. Why? Because of two reasons:
Cortisol is highest in the morning. That's when you want to check the natural trend of elevated cortisol levels.
Cortisol levels change the most in early morning, soon after waking up (which is also called cortisol awakening response).
Figure 2: Trend of high cortisol levels in the morning after waking up. The morning sample should be collected around 30 to 45 minutes after waking up to capture this peak.
In order to capture morning and night levels, you need at least two samples. They give a good idea of your normally high and low levels and can flag any unusual behavior from cortisol imbalance.
For example, lower cortisol levels in morning or very high cortisol levels at night suggest possible issues with adrenal glands and other health issues.
This is the most common cortisol test that captures the 24-hour daily trend.
First sample is collected in the morning, about 30 to 45 minutes after waking up. The other samples are collected in afternoon, evening, and before going to bed.
Figure 3: Trend of normal cortisol levels from a 4-point cortisol test with typical low and high ranges. Cortisol hormone imbalance will not show such a trend.
If you want to capture the cortisol awakening response in early morning, it might be useful to collect multiple samples every 10 to 15 minutes.
A nice sharp peak indicates healthy adrenal response (as shown in the first graph on the top). A flat curve may be due to multiple reasons.
Cortisol levels change with age, season, life style, working hours, and variation from unknown reasons.
One should collect the sample of about 1 ml within 5 mins; the longer it takes, the more flat the morning levels becomes due to averaging over time.
There can be many reasons for abnormal cortisol levels and a trend that doesn't show sharp peak in the morning.
Stress - chronic stress, PTSD, depression, chronic pain, social & economic pressures, insomnia.
HPA axis - problems with the Hypothalamus, Pituitary and Adrenal glands, e.g., Addison's disease (when adrenal glands don't produce enough cortisol), Cushing's syndrome (when adrenal glands produce too much cortisol).
Medication - certain medicines suppress or enhance cortisol release; generally speaking, antidepressants and antipsychotics suppress cortisol levels and stimulants increase them. See this page for a list of medicines that affect cortisol levels.
Daily routine - fasting (long gaps between meals or intermittent fasting), abnormal sleep behavior, vigorous exercise, pain, sudden stressful situations (e.g., exams, public speaking, etc.)
Health conditions - hypertension, gut issues, allergies, bipolar disorder, smoking, obesity, etc.
It's recommended to repeat the test for confirmation as there can be so many other reasons for abnormal results. You should always talk to your doctor after receiving the results and for next steps.
The 24-hour circadian rhythm can shift dramatically due to change in sleeping behavior, jetlag, shift in clocks from daylight saving, and working in night shifts.
In general, one should collect the samples when they are on their regular routine.
Otherwise, it will reflect their daily clock which may not match with the regular day and night patterns.
A shifted trend is not an indication of cortisol imbalance. It simply reflects a shift in their circadian rhythm.
With so many different types of cortisol tests on offer, it's not surprising to get confused.
However, we recommend to try a saliva test whenever available.
They are easy to collect, are as reliable as blood tests, and several samples can be collected from the comfort of your home.
A cortisol saliva test can help plot a daily trend, which is highly recommended, since the trend itself provides a more comprehensive health information.
Among various saliva tests, try a four-point test with saliva collected at four different times during the day.
As a backup, you can try a morning or evening sample to help understand the high and low levels.
For special cases, you can try a cortisol awakening response with multiple samples collected few minutes apart in the morning.
Order a 24-hour cortisol test kit.
Cortisol - Key Risk Factors - Learn more about risks in details.
Why Morning Cortisol Levels and Collection Time are so Important? - learn the details to test accurately.
Sleep and the Role of Melatonin and Cortisol Levels – short summary of sleep problems and two key hormones.
The Most Common Effects of High Cortisol Levels - know what chronic high stress can do to you.
5 Telltale Symptoms of High Cortisol Levels - see the signs before you test.
How Can My Medicine Affect Cortisol Levels? - certain drugs tend to raise or lower normal cortisol levels.
How to Check Cortisol Levels at Home? - learn about your options to measure cortisol levels.
The Impact of Chronic Stress on Your Body - chronic stress breaks down muscles to build fat & increases weight.
Saliva Testing – Advantages and Concerns - saliva is simple, easy to collect and can be as accurate as blood tests.
