Interpreting Cortisol Lab Tests in Adrenal Fatigue

By James Wilson, DC, ND, PhD

Steroid hormones occur in more than one form in the body, but most lab tests only measure one. This scenario further complicates the problem of proper interpretation of lab data related to adrenal fatigue diagnostics.

Cortisol, for example, takes on three forms in the blood:

1) Free, unattached to any other substance

2) Loosely bound

3) Tightly bound to blood proteins

The most common measurement for hormones is the amount of hormone not attached to anything (free circulating). However, free circulating hormone usually represents a meager 1% of the total amount of hormone available. Common lab tests do not measure the bound hormones, which act as reserves and become free hormones as needed. This reserve can be critical to proper physiological function.

For example, very low circulating cortisol levels can be brought to within normal range by the administration of a synthetic cortisol. But that poses a problem, because people taking synthetic cortisol cannot withstand stress as well as people with naturally normal cortisol levels, even though blood tests for both show normal free circulating cortisol levels. Although free circulating cortisol levels are increased by taking the synthetic cortisol, tissue-bound cortisol, which provides reserve stores in cases of emergency (stress), remain low.

Blood tests can often be deceptive because they do not typically give the whole picture. Therefore, even though both healthy people and people taking cortisol might show normal free cortisol levels, their response to stress will probably differ considerably. The test results would give a very deceptive picture of “normal” in the case of the person receiving the drug, as it tests only the most superficial layer of cortisol availability.

In adrenal function, the extreme low on a bell curve is Addison’s disease and the extreme high is Cushing’s disease. The other 95% represents an enormous variation in levels of adrenal function that is usually disregarded by lab computers and overlooked by doctors because the scores in this range do not fall into either of the two extreme or “diseased” categories. By default, any scores falling within this range (95%) are considered “normal.”

The end result of basing laboratory test scores on statistics rather than on signs and symptoms is that many people who have mild to moderately severe adrenal fatigue are never accurately diagnosed; they look “normal” on the tests.

Stress is a factor that significantly affects adrenal hormone levels. Cortisol level tested after a quiet, relaxing morning will be very different from cortisol tested during or just after a period of stress. To obtain a typical value, perform tests on a typical morning.


Original blog by Dr. James Wilson can be found here.

Dr James Wilson

James L. Wilson, DC, ND, PhD, received his Ph.D. in Human Nutrition from the University of Arizona, with minors in Immunology, Microbiology, Pharmacology and Toxicology, and research in Cellular Immunology. His doctorates in Chiropractic Medicine and Naturopathic Medicine are from the Canadian Memorial Chiropractic College and the Ontario College of Naturopathic Medicine (CCNM).

As one of the 14 founding members of CCNM, now the largest Naturopathic College in the world, Dr. Wilson has long been on the forefront of alternative medicine. For over twenty-five years, he was in private practice in Canada and the United States. In 1998, Dr. Wilson coined the term ‘adrenal fatigue’ to identify below optimal adrenal function resulting from stress and distinguish it from Addison’s disease.

With a researcher’s grasp of science and a clinician’s understanding of its human impact, Dr. Wilson has helped many physicians understand the physiology behind and treatment of various health conditions. He is acknowledged as an expert on alternative medicine, especially in the area of stress and adrenal function. Dr. Wilson is a respected and sought after lecturer and consultant in the medical and alternative healthcare communities in the United States and abroad.



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