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

Injectable Estradiol Dosing Regimens in Transgender and Nonbinary Adults Listed as Male at Birth

Context

Many transgender and nonbinary (TGNB) individuals assigned male at birth (AMAB) seek hormone therapy to achieve physical and emotional changes. Standard therapy includes estradiol, with or without an antiandrogen. Our clinical observations suggest that currently recommended injectable estradiol dosing may lead to supratherapeutic estradiol levels.

Objective

We sought to evaluate whether lower-than-recommended doses of injectable estradiol were effective in achieving serum estradiol and testosterone goals.

Methods

We conducted a retrospective cohort study to evaluate injectable estradiol dosing in treatment-naive AMAB individuals initiating hormone therapy. Data from a single provider at an academic center from January 2017 to March 2023 were analyzed. A total of 29 patients were eligible for inclusion. The primary variables of estradiol dosage, serum estradiol, and testosterone levels were analyzed over 15 months.

Results

The average estradiol dose decreased from 4.3 to 3.7 mg weekly (P < .001) during the study period with a final on-treatment estradiol level of 248 pg/mL. All individuals achieved a testosterone level of less than 50 ng/dL during the study period. The average initial on-treatment testosterone level was not significantly different from average final on-treatment measurement of 24.0 mg/dL (P = .95). Spironolactone use at study initiation was not associated with a lower initial on-treatment testosterone level, though it was associated with a lower estradiol level of 285 pg/dL compared to 427 pg/dL for those on estradiol monotherapy (P = .017).

Conclusion

Lower doses of injectable estradiol can achieve therapeutic estradiol levels with excellent testosterone suppression. Spironolactone was not associated with additional testosterone suppression and may result in lower estradiol levels.

Laboratory Monitoring in Transgender and Gender-Diverse Individuals

BACKGROUND

Increasing numbers of transgender and gender-diverse individuals are seeking initiation of gender-affirming hormone therapy. This aligns an individual's physical characteristics with their gender identity and improves psychological outcomes. Physical changes, including changes to muscle mass and body fat redistribution, can alter sex-specific laboratory reference ranges.

CONTENT

We review the impact of gender-affirming hormone therapy on laboratory parameters with sex-specific reference ranges, with a focus on hemoglobin/hematocrit, renal function, cardiac biomarkers, and prostate-specific antigen.

SUMMARY

Gender-affirming hormone therapy results in changes in laboratory parameters with sex-specific reference ranges. For individuals established on gender-affirming hormone therapy, reference ranges that align with an individual's gender identity should be used for hemoglobin/hematocrit, serum creatinine, and high-sensitivity cardiac troponin and N-terminal brain natriuretic peptide. Clinicians should interpret these biomarkers according to the reference range that aligns with one's affirmed gender.

Injectable Estradiol Use in Transgender and Gender-Diverse Individuals in the U.S.: A Multicenter Retrospective Study

CONTEXT

Guidelines for use of injectable estradiol esters (valerate [EV] and cypionate [EC]) among transgender and gender diverse (TGD) individuals designated male at birth vary considerably, with many providers noting supraphysiologic serum estradiol concentrations based on current dosing recommendations.

OBJECTIVES

1. Determine dose of injectable estradiol (subcutaneous [SC] and intramuscular [IM]) needed to reach guideline-recommended estradiol concentrations for TGD adults using EC/EV. 2. Describe relationship between estradiol concentration relative to timing/dose of last estradiol injection and other covariates. 3. Determine dosing differences between IM/SC EV/EC.

METHODS

Cross-sectional retrospective study across six United States medical centers including TGD adults on same-dose injectable estradiol for >75 days, with confirmed timing of estradiol concentration relative to last injection, from 1/1/2019---12/31/2023. Descriptive statistics were used to describe patient characteristics and weighted linear mixed models to evaluate relationship between various covariates and estradiol concentration.

RESULTS

Data from 562 patients were included. Among those injecting every seven days who reached the guideline-recommended estradiol concentration (n=131, 27.5%), the median estradiol dose was 4.0 mg (interquartile range 3.0---5.0 mg). Among all patients, the majority reached supraphysiologic estradiol concentrations (>200 pg/mL [>734 pmol/L]) while dose and timing in the injection cycle were significant covariates for the estradiol concentration. There were no significant dosing differences between IM/SC EV/EC.

CONCLUSION

Injectable estradiol esters effectively reach guideline-recommended estradiol concentrations but at lower doses than previously recommended. Estradiol concentrations are best interpreted relative to timing of last injection. Route of administration and type of ester do not significantly impact estradiol concentrations.

Revisiting Injectable Estrogen Dosing Recommendations for Gender-Affirming Hormone Therapy

Injectable estrogens are options for gender-affirming hormone therapy per guidelines, which suggest intramuscular dosages of 5-30 mg every 2 weeks or 2-10 mg weekly with estradiol cypionate or valerate interchangeably. Data among transgender and gender-diverse patients are limited due to local unavailability and concerns around laboratory assay variability and estradiol (E2) level fluctuation. We note a concerning trend where patients are prescribed high-dose injections based on the guidelines leading to serum E2 levels well above the range recommended in the same guidelines. Our review indicates that 5 mg weekly or lower should be prescribed when initiating injectable estrogens to avoid supraphysiologic E2 levels.

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.

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

OBJECTIVE

Feminizing gender-affirming hormone therapy is the mainstay of treatment for many transgender and gender diverse 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.

METHODS

We performed a scoping review of the available data on estradiol levels achieved with various dosages of estradiol injections in transgender and gender diverse adults on feminizing gender-affirming hormone therapy. We also report on testosterone suppression, route (ie, subcutaneous vs intramuscular), and type of injectable estradiol ester as well as timing of blood draw relative to the most recent dose, where available.

RESULTS

The data we reviewed suggest that the current guidelines, which recommend starting doses 2 to 10 mg weekly or 5 to 30 mg every 2 weeks of estradiol cypionate or valerate, are too high and likely lead to patients having supraphysiologic levels across much of their injection cycle.

CONCLUSIONS

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 cypionate or 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.

Advanced drug delivery technologies for postmenopausal effects

Postmenopause is the 12-month absence of menstrual periods, characterized by decreased estrogen and progesterone levels, leading to physical and psychological alterations such as hot flashes, mood swings, sleep disruptions, and skin changes. Present postmenopausal treatments include hormone replacement therapy, non-hormonal drugs, lifestyle modifications, vaginal estrogen therapy, bone health treatments, and alternative therapies. Advanced drug delivery systems (ADDSs) are essential in managing postmenopausal effects (PMEs), offering targeted and controlled delivery to alleviate symptoms and improve overall health. This review emphasizes such ADDSs for addressing PMEs. Emerging trends such as artificial ovaries are also reviewed. Additionally, the prospects of technologies such as additive manufacturing (3D and 4D printing) and artificial intelligence in further tailoring therapeutic strategies against PMEs are provided.

A Call for Updates to Hormone Therapy Guidelines for Gender-Diverse Adults Assigned Male at Birth

Gender-affirming hormone therapy for assigned male at birth (AMAB) individuals with gender incongruence typically consists of estradiol with or without an anti-androgen to achieve physical changes and psychological benefits. However, prescribed hormone regimens vary considerably, and high-quality research in this area is extremely limited. Additional evidence-based research evaluating patient-reported outcome measures (PROMs) is needed to fill current knowledge gaps and create a personalized therapeutic approach for AMAB individuals. This editorial provides a critical description of current treatment options, discusses their variability, reviews some discrepancies in guideline-based dosing recommendations, and recommends areas for further study.

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.