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 Testing in Research

Posted by Dr. Alison McAllister on Friday, 23 December

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I wanted to share a few of the studies using saliva testing that were published in the literature in 2016.

Just a hint, if you want to search for articles on saliva testing, use pubmed.gov and search saliva estradiol (or progesterone, testosterone etc.).

Be aware that saliva 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.

It’s always good to know that the work that ZRT has been doing for almost 20 years in the field of saliva testing is still cutting edge and useful. 

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Testosterone Replacement Therapy: Ensuring an Accurate Dose!

Posted by Jim Paoletti on Thursday, 07 July

scientists_deciding.jpgTestosterone replacement therapy has the potential to drastically improve quality of life of those who need it. However, many men who begin topical testosterone are given too much of the hormone.

Explanations for this erroneous tendency are rooted in incorrect dosing principles that have been established on false assumptions, misconceptions, invalid conclusions and aggressive marketing instead of physiology and science.

Why are testosterone replacement standards and prescribing processes so frequently misguided? 

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SHBG – A Modulator to be Modulated

Posted by Dr. Allison Smith on Tuesday, 21 July

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SHBG, or Sex Hormone Binding Globulin, controls testosterone effect in both men and women by modulating changes in sex steroid levels. When SHBG goes up, free testosterone goes down.

I like to think of SHBG as a sponge that soaks up androgens and to some degree estrogens as well.

Since it binds so specifically and tightly to testosterone, it makes up part of the equation that equals androgen excess or androgen deficiency. Knowing how to manipulate SHBG can be a useful tool in a number of scenarios.

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Topical Testosterone & the U-Shaped Curve

Posted by Dr. Allison Smith on Thursday, 11 June

TestosteroneThe testicles of a man in his 20s are known to contribute about 5-10mg of testosterone per 24-hour day and levels of total testosterone in the venous blood with that amount are observed to yield roughly 300-1200 ng/dL in the morning at the diurnal peak.

Testosterone, whether endogenous or given exogenously, negatively feeds back on the hypothalamus, limiting GnRH and thus LH and FSH from the pituitary. A man taking supraphysiological doses of testosterone can expect to have very low or undetectable levels of LH and FSH in the serum. What happens when the prescription dose overshoots the patient's optimal dose? Certainly, we see LH and FSH practically disappear.

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