The Relation of GnRH Treatment to QTc Interval in Transgender Female Youth: A Time Series Study

This study is a quasi-experimental time series study, designed to examine the relation between GnRH agonist treatment for 6 months in transgender female youth and electrocardiographic change in QTc interval. Study subjects will be identified when visiting the UCSF Child and Adolescent Gender Center (CAGC). A baseline electrocardiogram (ECG) will be obtained in clinic before initiation of GnRH agonist treatment and at the 6 months follow up appointment.

Sampling scheme: Consecutive sample of transfemale patients presenting to UCSF CAGC (Child and Adolescent Gender Center) clinics meeting entry criteria, who consent to participate in this study

Recruitment strategy: The investigators will approach all transfemale patients with pubertal Tanner stage 4-5 who are ready to start GnRH agonist. From past experience in CAGC clinic, willingness of patients to participate in studies is high. The investigators plan that ECG will be available at clinic visits to further assist recruitment.

Retention strategy: Patients that are being treated in CAGC clinic are followed up every 3 months. Patients are very compliant with clinic visits as patients are eager to complete their transition. ECG is planned to be available at the 6 months clinic follow up visit.

Measurements: The investigators will assess QTc interval using a standard 12-lead ECG. The investigators will also measure serum levels of calcium, potassium and magnesium to rule out electrolyte abnormalities as a cause for QTc interval change, and testosterone, estradiol, LH and FSH levels to assess GnRH agonist effect. The laboratory analytes will be measured using standard procedures in place at the UCSF Laboratory, which is certified by Centers for Medicare and Medicaid Services, the California Department of Health Services, and the College of American Pathologists.