Comparison of Subcutaneous and Intramuscular Estradiol Regimens as part of Gender-Affirming Hormone Therapy

The Use of Injectable Estradiol in Transgender and Gender Diverse Adults: A Scoping Review of Dose and Serum Estradiol Levels

Feminizing gender-affirming hormone therapy (GAHT) is the mainstay of treatment for many transgender and gender diverse (TGD) people. Injectable estradiol preparations are recommended by the World Professional Association for Transgender Health Standards of Care 8 and the Endocrine Society guidelines. Many patients prefer this route of administration, but few studies have rigorously assessed optimal dosing or route. We performed a scoping review of the available data on estradiol levels achieved with various dosages of estradiol injections in TGD adults on feminizing GAHT. We also report on testosterone suppression, route (i.e., subcutaneous vs. intramuscular), and type of injectable estradiol ester as well as timing of blood draw relative to the most recent dose, where available. The data we reviewed suggests that the current guidelines, which recommend starting doses 2-10 mg weekly or 5-30 mg every two weeks of estradiol cypionate or valerate, are too high and likely lead to patients having supraphysiologic levels across much of their injection cycle. The optimal starting dose for injectable estradiol remains unclear and whether it should differ for cypionate and valerate. Based on the data available, we suggest that clinicians start injectable estradiol valerate via subcutaneous or intramuscular injections at a dose ≤ 5 mg weekly and then titrate accordingly to keep levels within guideline recommended range. Future studies should assess timing of injections and subsequent levels more precisely across the injection cycle and between esters.

Approach to the Patient: Hormonal Therapy in Transgender Adults With Complex Medical Histories

While endocrinologists continue to initiate gender-affirming hormone therapy (GAHT) in healthy transgender and gender diverse (TGD) patients, they may also encounter more TGD patients in their clinics with complex medical histories that influence the patient-provider shared decision-making process for initiating or continuing GAHT. The purpose of this Approach to the Patient article is to describe management considerations in 2 adults with thromboembolic disease and 2 adults with low bone mineral density in the setting of feminizing and masculinizing GAHT.

A Mouse Model to Investigate the Impact of Gender Affirming Hormone Therapy with Estradiol on Reproduction

Gender-affirming hormone therapy (GAHT) can help transgender and/or gender diverse (TGD) individuals achieve emobidment goals that align with their transition needs. Clinical evidence from estradiol (E)-GAHT patients indicate widespread changes in tissues sensitive to E and testosterone (T), particularly in the reproductive system. Notably, E-GAHTs effects on hormones and reproduction vary greatly between patients. With the goal of informing clinical research and practice for TGD individuals taking E, this study examines intact male mice implanted with capsules containing one of three different E doses (low 1.25 mg; mid 2.5 mg; high 5 mg), or a blank control capsule. All E-GAHT doses suppress T and follicle stimulating hormone levels while elevating E levels. Only the high E-GAHT dose significantly supresses luteinizing hormone levels. All E-GAHT doses affect epididymis tubule size similarly while seminiferous tubule morphology and bladder weight changes are dose-dependent. E-GAHT does not alter the presence of mature sperm, though E-exposed sperm have altered motility. These data represent the first evidence that mouse models offer an effective tool to understand E-GAHTs impact on reproductive health and the dose-dependent effects of this model permit examinations of diverse patient outcomes.