Dynamic Impact of Hormone Therapy on Laboratory Values in Transgender Patients over Time

Background Known physiological changes occur while transgender patients are taking hormone therapy (HT). However, knowledge is limited about when laboratory values stabilize and if there are any long-term impacts, making it challenging for physicians to provide adequate gender-affirming care. We aim to analyze laboratory values with HT use over 5 years and after discontinuation of HT to define when values achieve stability. Methods We performed a multicenter retrospective analysis of 126 transgender women (TW) and 91 transgender men (TM) at consecutive clinic visits. Labs included complete metabolic panel, complete blood count, lipids, and hormone levels and were monitored for 5 years. Absolute measurement and percentage change from baseline were calculated for each analyte value. We collected the laboratory studies described from patients off HT and the duration of discontinuation to determine the time to return to baseline levels. Results During HT, red blood cell (RBC; erythrocyte) indexes reach stable levels within 6 months (P < 0.001) and are unchanged long term. Some analytes such as HDL and platelets showed increases beyond the first year of HT in TW (P = 0.001 and P < 0.001, respectively). LDL and alanine aminotransferase increased beyond 1 year in TM (P < 0.005 and P < 0.001, respectively), whereas HDL decreased beyond 1 year (P < 0.001). Time for laboratory values to return to baseline occurred around 10 weeks. Conclusions Most analytes reach stable levels within 6 months (RBC and creatinine), whereas others change in the long term (LDL, HDL, platelets). This information can be used to guide physicians as they monitor their transgender patients in all stages of their progress through HT.