Stress has a way of wreaking havoc on our bodies, leaving us feeling utterly drained and exhausted. And our modern way of life is busier and more stressful than ever!  It’s no wonder that many people have turned to cortisol testing to help prevent and recover from burnout. 

But what if I told you that the commonly used salivary (spit) cortisol test, often relied upon to identify “adrenal fatigue,” may not be as reliable as you’ve been led to believe? 

In fact, I’ve witnessed numerous patients undergoing cortisol testing at their doctor’s office, only to receive inconclusive results or to be prescribed treatments based solely on the saliva test, which ultimately made them feel worse. 

In this blog post, we’ll dive into the reasons behind the inaccuracy of popular cortisol tests, exploring everything from inconsistent lab ranges to timing complications. By unraveling the scientific complexity of cortisol testing, we’ll shed light on the most accurate methods for assessing your cortisol levels. 

Are you ready to crack the code and discover the truth behind cortisol testing? Join us on this enlightening journey!



When it comes to testing cortisol, it’s pretty common for people to get a salivary cortisol test at their doctor or to self-diagnose adrenal fatigue based on symptoms. 

However, it is important to note that the majority of people do not have low cortisol levels and that is what most people are assuming under the adrenal fatigue theory. (Read more on why I don’t like the term “adrenal fatigue” here)

Let’s talk about why measuring cortisol by saliva or blood is not very reliable. 

Saliva-based cortisol tests measure “free” cortisol which is the most active form of cortisol as it can activate cellular transcription response and is the only form that has cell signaling effects.

The issue is that free cortisol only constitutes 3-5% of the total cortisol in the body. Testing such a small amount of cortisol is not representative of the overall cortisol production in the body.

Now what about measuring cortisol in the blood? This is unreliable as well because cortisol in the blood is bound to cortisol-binding globulin (CBG), which can vary greatly among even healthy individuals and is influenced by various diseases, illnesses, and medications. This makes blood a poor way to measure cortisol as well. 


So now that we’ve explained why blood and saliva are both unreliable substances to test for cortisol, let’s talk about another issue.

Your results could vary widely from one lab company to the next. There isn’t a standard of testing for salivary cortisol. The “reference ranges” (you know, the ones where your doctor will tell you that your lab results are “within normal range”) vary from company to company as do the units they use.

That means even when taking the tests at the same time on the same day, you may be within the ‘normal’ range with one company but have low cortisol with another. In addition, you’d have to convert Labcorp’s nM/L to BioHealth’s ug/dL (or vice versa) to even compare the results which makes the whole testing process skeptical, frustrating, and confusing at best.

Here’s an example:


The “lower-end range” is the lowest number a company states for being within range or “healthy”. The normal range for an 8 am cortisol test should be between 0.025-0.600 according to LabCorp.

LabCorp’s lower-end-range is 0.025 while BioHealth’s is 0.472

That’s almost 20x higher!

These variances in lab ranges make it hard to evaluate the results and know what’s truly healthy or within range.



The timing of which you take the first test is crucial for getting an accurate cortisol reading. Here’s why:

■Upon waking, our eyes absorb light which activates the suprachiasmatic nucleus located in the hypothalamus (brain) and is the pacemaker of our circadian rhythm. This activation increases cortisol secretion by up to 50% and is called the ‘cortisol awakening response’, or CAR. It happens within the first 30-45 min of waking.

■ The cortisol that is produced during the CAR accounts for more than 1/2 of the total cortisol reported on a full day’s saliva test and since most saliva tests take an average of 4 collections during test day this makes the timing of the first sample crucial. 

■ This is a massive problem because most labs suggest doing the first sample ‘between the window of 6-8 am’ instead of based on the time you wake up.

■ So this means that if you wake up at 6 am and don’t test until 7:55 am, you just missed that initial 30-45 min window and are missing tons of data.


Getting natural light exposure within that first hour of waking is overwhelmingly important to the entire functionality of your body. This helps in regulating your body’s circadian rhythm, making you feel more alert and awake as well as regulating hormones, appetite, digestion, mood and sleep at nighttime. Spending just a few minutes outdoors in the morning can have a big impact on regulating your sleep-wake cycle. If you have trouble sleeping, I strongly suggest giving this a try. Go for a morning walk or exercise outside, and if possible, enjoy your coffee or breakfast outdoors. If you live in a cold environment, try to sit by a window or open your blinds first thing in the morning. Although the window will block some of the UV rays, it’s still better than nothing. Just do what works best for you!


At Flora Fauna, we use the DUTCH hormone test for checking cortisol levels. Unlike traditional blood or saliva tests, this method is much more accurate and gives us a better understanding of how your body produces and uses cortisol throughout the day.

Cortisol, also known as the “stress hormone,” fluctuates throughout the day. But blood and saliva tests only capture a single moment, which might not represent what’s really going on. The DUTCH test, on the other hand, looks at cortisol metabolites in your urine over a whole day (or throughout the month if we are doing the DUTCH Cycle Mapping Plus to also track your sex hormones throughout the month). It’s like getting a full-day report instead of just a snapshot. This helps us see the real picture of your cortisol levels and how your body handles it.

What’s cool about the DUTCH test is that it’s based on functional medicine principles. It’s not just about finding diseases; it’s about making sure your body works optimally. The test also checks other important hormones like estrogen, progesterone, and testosterone, along with their metabolites. It considers how different hormones interact with each other and gives us a holistic view of your hormone balance. This can help us catch imbalances or issues early on, before they cause trouble.  This comprehensive approach helps us understand the bigger hormonal picture and identify any potential problems.

If you’re experiencing “adrenal fatigue” symptoms like burnout, exhaustion, insomnia, anxiety, hormone imbalances or other symptoms, schedule a Functional Medicine Consult with us! 

Let’s get down to the root of your health issues and get you feeling your absolute best!