WASHINGTON – A pioneering study published today in AACC’s The Journal of Applied Laboratory Medicine has established transgender reference intervals for common clinical laboratory tests. Reference intervals are essential to high quality medical testing and by determining them for transgender individuals, this research could lead to significant improvements in healthcare for this vulnerable patient population.

View the full study here: https://doi.org/10.1093/jalm/jfac025

At least 80% of transgender people have either taken gender-affirming hormone therapy or want to take it at some point so that they can express their gender in a way that makes them feel comfortable. One side effect of this hormone therapy is that it changes results for common laboratory tests. As a result, there is a critical need for accurate transgender-specific reference intervals, which are the ranges of lab values observed in a healthy population that are used to determine whether individual lab results are normal or concerning. Without accurate reference intervals, clinicians could misinterpret transgender patient test results, which in turn could lead to misdiagnosis and/or inappropriate treatment. To date, a number of studies have looked at the impact of gender-affirming hormone therapy on lab test results. However, most of these studies have included people with medical conditions, which means that their findings can’t be used to determine reference intervals for the transgender population.

A team of researchers led by Matthew Krasowski, MD, PhD, of the University of Iowa Hospitals and Clinics, set out to fill this gap in transgender care. To do this, Krasowski’s team recruited 175 healthy transgender and nonbinary adults, 93 of whom had been prescribed estradiol (a form of estrogen) and 82 of whom had been prescribed testosterone for at least 12 months. In these study participants, the researchers measured electrolytes, creatinine, urea nitrogen, liver function enzymes, hemoglobin A1c, lipids, and high-sensitivity C-reactive protein. Clinicians routinely test for these analytes to diagnose a broad range of common conditions ranging from diabetes to liver damage to cardiovascular disease.

From this, the researchers found that liver function enzymes exhibited the most significant shift toward affirmed gender. This means that transmasculine individuals taking testosterone had enzymes in the same range as healthy cisgender men, while transfeminine individuals taking estradiol had enzymes in the same range as healthy cisgender women. In participants taking testosterone, creatinine also shifted toward affirmed gender and HDL cholesterol decreased, though changes to these analytes did not occur in the estradiol group. As for the remaining analytes, gender-affirming hormone therapy had minimal impact on them. Using these results, the researchers calculated transgender-specific reference intervals for each of these tests according to Clinical Laboratory Standards Institute guidelines. 

“Gender-affirming hormone therapy with either estradiol or testosterone is the standard of care for the medical transition of transgender and nonbinary people,” said Krasowski. “Here, we established reference intervals for common clinical chemistry analytes in transgender people administered either feminizing or masculinizing hormone therapy. These results help promote evidence-based medical care for the transgender and nonbinary population.”

About AACC

Dedicated to achieving better health through laboratory medicine, AACC brings together more than 70,000 clinical laboratory professionals, physicians, research scientists, and business leaders from around the world focused on clinical chemistry, molecular diagnostics, mass spectrometry, translational medicine, lab management, and other areas of progressing laboratory science. Since 1948, AACC has worked to advance the common interests of the field, providing programs that advance scientific collaboration, knowledge, expertise, and innovation. For more information, visit www.myadlm.org.

Launched by AACC in 2016, The Journal of Applied Laboratory Medicine (jalm.org) is an international, peer-reviewed publication showcasing the applied research in clinical laboratory science that is driving innovation forward in healthcare.