The ZRT Laboratory Blog

The ZRT Blog is an extensive resource for patients and health care providers searching for health and hormone testing information. Here, you can read about ZRT’s cutting edge research, advances in testing, wellness advice, and health industry highlights.

A Year of Saliva in Research

Posted by Dr. Alison McAllister on Friday, 23 December


It’s always good to know that the work that ZRT has been doing for over 15 years in the field of salivary testing is still cutting edge and useful.  Today I just wanted to share a few of the studies using salivary estradiol that are being published in the literature. Just a hint, if you want to search for articles on salivary testing use and search saliva estradiol (or progesterone, testosterone etc.). Be aware that salivary hormone testing is so standard in the research world that rarely is it mentioned in the titles of the papers. Over 310 studies were published in 2016 using saliva testing – 61 studies for testosterone and 189 studies on cortisol, while poor progesterone was neglected with only 14 studies this last year.

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How Reference Ranges Determine a "Normal" Lab Test Result

Posted by Margaret Groves on Friday, 13 November

normal.chalkboard.jpgCLIA-certified testing laboratories such as ZRT are required to provide reference ranges as an aid to interpretation of test results.

Ideally, reference ranges provide the expected range of values for a healthy population. When methodology and equipment is identical for testing a particular analyte among different laboratories, reference ranges for that analyte should be the same.

However, when methodologies or equipment for the same test differ somewhat from lab to lab, each lab must provide its own reference range established with its own methods. These ranges are usually very close, but may differ slightly depending on method. An example would be testing testosterone in blood or saliva by extraction and LC-mass spectrometry vs. direct testing by immunoassay.

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Cortisol Testing in Saliva, Blood, and Urine

Posted by Dr. David Zava on Friday, 29 May


Cortisol plays a vital role in health and well- being.  Inadequate or excessive production or disrupted circadian patterns of cortisol synthesis by the adrenal glands in response to stressors can eventually lead to imbalances in blood glucose levels, impaired immune response, as well as a host of different hormonal imbalances, all of which are associated with multiple adverse conditions and symptoms.   

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How a Symptom Checklist Can Help You Determine a Hormone Testing Method

Posted by Dr. Sherry LaBeck on Tuesday, 12 May

ThinkstockPhotos-495589925Are you ever confused about where to begin when trying to balance your patient’s hormones? Symptoms of hormonal imbalance can often be challenging to assess. Is your patient exhibiting signs of estrogen dominance because her estrogen is too high or is it due to the progesterone being too low? Is his fatigue because he’s not making enough testosterone or that his adrenal glands are working over-time? Are her imbalanced sex steroids the cause of her depression or is it the low thyroid hormone?

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