We not only lead the industry. We defined it.

ZRT Laboratory developed the methodology that made saliva hormone testing commercially viable for healthcare providers and patients around the globe.

We also helped develop the science for accurately measuring steroid hormones in dried blood spot, and are currently the only laboratory offering this technology commercially.

And we don’t stop there. Hormone testing in dried urine is yet another scientific advancement for the industry that was pioneered by ZRT.


ZRT Testing Approved by CDC

ZRT is the only specialty hormone laboratory to have qualified for the CDC’s Hormone Standardization Program (HoSt) – meaning that ZRT has successfully passed the performance criteria to qualify for the CDC Testosterone Reference Method and the CDC Estradiol Reference Method

It all starts with accuracy. (But we offer flexibility and convenience, too.)

Today we are one of few laboratories capable of testing across three methodologies, which means that ZRT tests in the most appropriate medium, not just the most convenient. And because collected samples are stable for weeks (saliva) or months (dried blood spot and dried urine) and do not need to be shipped frozen, research can be carried out even in remote areas and samples shipped via regular mail.

Our testing methodologies:
Saliva Testing identifies bioavailable hormone levels – the active quantity that's free to move into body tissue. Its non-invasive nature also makes it the gold standard for tests requiring multiple collections, such as diurnal cortisol.
Dried Blood Spot is ideal for measuring hormones and other analytes such as insulin, blood lipids, Vitamin D, thyroid hormones, and elements like lead and magnesium. These results have been proven equivalent to serum, and offer distinct advantages over serum testing for monitoring topical and sublingual hormone supplementation.
Dried Urine testing is the best way to measure adrenal and sex steroid hormone by-products from their respective metabolic pathways, providing a gauge for understanding the body’s hormone metabolism. It’s also the preferred method for testing elements like iodine and heavy metals like arsenic and cadmium. Additionally, it’s the accepted method for testing neurotransmitters. ZRT's method of testing dried urine offers discreet, at-home collection versus all-day serial sampling.
Serum testing is a standard method for many research studies and we perform this testing for those who require it.

To help establish industry-wide standards, we initiated the Salivary Proficiency Inter-laboratory Testing (SPIT) program. As part of this program, results from carefully selected pooled samples are compared to results for the same samples from other saliva testing laboratories two times per year. This effort allows us to regularly evaluate our saliva testing accuracy.

ZRT is also the only laboratory to perform an extraction process for saliva testing, which separates hormones from background contamination. This is the accepted methodology for research studies and the only way to ensure accurate test results for low-concentration hormones such as estradiol, which exists at 1/10,000 the level of DHEA.

ZRT does not pool patient samples, meaning that we don’t mix multiple daily samples together to get an average hormone level. Instead we measure reproductive hormones from a single morning sample, which represents the peak of daily hormone production – the optimal time to measure.

Our online resource materials are continually growing, as are the articles published in peer-review journals and conference presentations.

View our published research papers and a list of abstracts and posters presented at scientific meetings.