Common Hormone Therapies Used to Care for Transgender Patients Influence Laboratory Results

Background: Many laboratory tests are reported and interpreted with sex-specific reference intervals. However, transgender individuals receiving masculinizing or feminizing hormone therapy experience physiological changes predisposing some laboratory tests to shift outside of existing reference intervals. In this study, we review laboratory testing of a large cohort of transgender individuals who were prescribed hormone therapy for at least 6 months at an academic medical center. Methods: Transgender patients were identified using a search function within the electronic health record with gender identity status verified by chart review. Patients were grouped based on type of hormone therapy administered. All laboratory studies were ordered for medical purposes as part of clinical care; as a result, the exact laboratory tests differed among the patients. Some of the patients had sufficient data for both 6- and 12-month comparisons with baseline laboratory values. Results: Statistically significant changes were observed at 6- and 12-month comparisons in basic chemistry, endocrine, and hematologic parameters for transgender individuals receiving masculinizing or feminizing hormones. Chart review demonstrated variation in route of administration of hormone therapy and frequency of gender-affirming surgery within the study population. Conclusions: Transgender individuals receiving hormone therapy experienced significant changes in components of basic chemistry, endocrine, and hematologic parameters following administration of hormone therapy. Variability in hormone dosing and route of administration for gender-affirming treatment warrants further investigation.