Groundbreaking research presented at the 71st AACC Annual Scientific Meeting & Clinical Lab Expo has revealed how transgender hormone therapy affects the results of common laboratory tests in the long term. This first-of-its-kind study could enable the development of transgender-specific reference intervals, which are crucial to ensuring that transgender patients get accurate diagnoses and equitable healthcare.

All major medical associations agree that transgender individuals need to be able to express their gender in ways that make them feel comfortable, and for many of these individuals, this involves physically changing their body through hormone therapy. However, research presented in 2018 at the 70th AACC Annual Scientific Meeting showed that 6 months of transgender hormone therapy markedly changes results for common laboratory tests. This finding demonstrates a critical need for 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 these reference intervals, clinicians could misinterpret transgender patient test results, which in turn could lead to serious health consequences as a result of misdiagnosis and/or inappropriate treatment.

The researchers behind the 2018 study, a team led by Jeffrey SoRelle, MD, of the University of Texas Southwestern Medical Center in Dallas have now completed a follow-up study that lays the foundation for establishing transgender-specific reference intervals. SoRelle's team tracked comprehensive metabolic panel, complete blood count, and lipid test results for 147 healthy transgender patients on hormone therapy over the course of 5 years. This is the longest time that any study has monitored lab values in transgender individuals to date.

Out of all the test values the study examined, red blood cell and creatinine levels (a measure of kidney health) underwent the largest shifts when transgender individuals started hormone therapy. These values then typically stabilized after 6 months. In transgender women specifically, platelet and low-density lipoprotein levels (a measure of cardiovascular health) increased after several years of hormone therapy, while alkaline phosphatase (a marker of liver and bone health) decreased steadily for a few years before returning to baseline levels in the long term. Knowledge of these trends could greatly improve healthcare providers' ability to interpret transgender patients' results for routine lab tests, and to monitor these patients for conditions ranging from anemia to heart disease and kidney failure.