Assessing Laboratory Values in Transgender Women Treated with Cross-Sex Hormone Therapy

OBJECTIVE: Laboratory results are used to guide clinical decision making, and reference ranges are developed to describe the variation seen in healthy individuals so that pathologic values can be distinguished from normal physiologic values. For transgender individuals taking cross-sex hormone therapy, changes in physiology can be expected to accompany the masculinization or feminization induced by the treatment, but the effect of these changes on laboratory tests is not well defined and cannot be easily predicted. This study seeks to evaluate the response of common laboratory tests to hormone replacement therapy (HRT) in transgender women (male-to-female, MTF), comparing to natal male and female populations. METHODS: We conducted a retrospective chart review for MTF and FTM (female-to-male) patients before initiating HRT and MTF patients after receiving HRT for 6-24 months at transgender-specific clinics in an urban county hospital (Parkland Hospital, Dallas, TX) and a community clinic (Resource Center, Dallas, TX). We collected demographic information, medical history, and laboratory values for CBCs, complete metabolic panels, liver function tests, lipids, and hormone levels taken throughout their course of treatment. RESULTS: In one of the largest studies of laboratory values in transgender patients, patient charts of 120 transgender women were reviewed, with a median age of 27 years. After initiating HRT, MTF patients showed a significantly increased estrogen and decreased testosterone (p<0.0001). Changes in hematologic parameters included decreases in red blood cell count, hemoglobin, and hematocrit (p<0.0001) and an increase in platelets (p=0.0001). Changes in metabolic parameters include decreases in sodium, creatinine, and alkaline phosphatase (p<0.0001). CONCLUSION: Better understanding the extent of expected changes in laboratory values can enable clinicians to more accurately evaluate the effects of HRT and choose appropriate treatments for individuals in the transgender population.