Wednesday, October 3, 2012

The Validity of Saliva Cortisol Testing

For 30 years saliva has been used as a reliable, cheap and effective way to measure the body's major stress hormone, cortisol.

Although use of saliva cortisol is by no means limited to natural or "functional medicine," that is probably where it has been used the most. Natural health care practitioners will often give patients saliva test kits to measure cortisol and hence their stress response.

Nonetheless, if a patient happens to then go to a medical doctor with the results, they may be told that there is no validity to saliva tests.

I want to make these points very clear:

1) If a medical doctor says there is no validity or reliable way to measure cortisol through saliva that doctor is ignorant. 

In such a case what that doctor really should do, is tell their patient that they are not familiar with saliva cortisol testing.

2) The debate on saliva cortisol testing has nothing to do with differences between functional medicine/ holistic medicine/ naturopathy / eastern medicine or anything else you'd like to call it and conventional mainstream medicine.

In reality, such lab testing is far within the scope of anything that can be called "western medicine." Not only that, it has been accepted by mainstream western medicine.

The use of saliva cortisol testing is actually a guideline in the practice of mainstream endocrinology! See link to Journal of Endocrinology and Metabolism abstract

Among the many studies done on saliva cortisol in the last 30 years, this one also stands out as well.

Melatonin and cortisol assessment of circadian shifts in astronauts before flight.

 3) Most medical doctors don't understand cortisol, stress and the circadian rhythm

Many times medical doctors tell patients things which are just simply not scientific with regards to such testing. This includes:

  • "Cortisol doesn't affect your health."
In truth cortisol is the body's stress hormone. If this true then stress itself doesn't affect health. At this point, the fact that stress greatly impacts health is accepted by everyone in health and proven over and over in countless research studies.

  • "Timing of testing cortisol doesn't matter"
In truth cortisol is closely linked to our circadian rhythm. In a healthy person it will be about 10 times higher upon waking then at night. Cortisol may even be normal one time of the day, but wildly out of reference range another time. Cortisol must be tested multiple times during the day, and at the correct time. (the above article citing use of saliva cortisol to test for Cushing's disease, is very clear to tests it late at night, not morning or afternoon, as people have blood cortisol tested then.)

  • "There is no science behind this"
There is overwhelming scientific support for saliva cortisol testing (and other saliva tests as well). A cursory glance at clinical studies will show that. I have linked to two studies in this blog article, but it would not be difficult to link to dozens. 

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