Introduction

Bioidentical hormones have become a topic of increasing interest in the realm of gender-affirming care. Unlike traditional hormone therapies, bioidentical hormones are chemically identical to those the human body naturally produces. This article explores the role, benefits, and considerations of bioidentical hormones in gender-affirming treatments.

What Are Bioidentical Hormones?

Bioidentical hormones are man-made hormones derived from plant estrogens that are chemically identical to those the human body produces naturally. Common hormones that are available as bioidentical hormones include estrogen, progesterone, and testosterone. These are used in various forms such as pills, patches, creams, gels, and injections.

The concept behind using bioidentical hormones in gender-affirming care, particularly in the context of transitioning from a testosterone-dominant (testicular) hormone profile to an estrogen-dominant (ovarian) one, plays a significant role in the relative rarity of side effects observed in many individuals. This approach is based on aligning the body’s hormone levels with the individual’s gender identity by mimicking the natural hormonal environment of the gender they identify with, and this approach tends to have fewer unwanted effects:

• Natural Mimicry: Bioidentical hormones are chemically identical to the hormones naturally produced by the human body. For instance, estradiol used in feminising hormone therapy is the same estrogen that ovaries produce. This similarity often means that these hormones are metabolically and physiologically more compatible with the body’s existing hormonal pathways.
• Reduced Immunogenicity: Since bioidentical hormones have the same molecular structure as natural hormones, the body is less likely to recognise them as foreign substances. This reduces the likelihood of immune reactions, which can be a source of side effects with synthetic hormones.
• Balanced Hormone Replacement: In gender-affirming therapy, the aim is to replace the dominant hormone profile (e.g., testosterone in transgender women) with one that aligns with the individual’s gender identity (e.g., estrogen). This ‘swapping’ is done in a controlled manner to reach hormonal levels typical of the gender that the individual identifies with. The body’s adaptation to these levels is generally favorable, as the process mimics natural hormonal conditions.
• Personalised Dosages: The use of bioidentical hormones often allows for more personalised dosing regimens. This individualised approach ensures that hormone levels are optimised for each person, reducing the risk of excessive dosages and related side effects.
• Monitoring and Adjustment: Regular monitoring and adjustment of hormone levels by healthcare professionals help in maintaining the right balance, further minimising adverse effects.

Examples of Bioidentical Hormones

Bioidentical hormones are designed to be chemically identical to the hormones naturally produced by the human body. Here are some examples:

• Estradiol: This is a form of estrogen, which is a key hormone for feminising therapy in transgender women and non-binary individuals assigned male at birth. It is bioidentical to the estrogen produced by the ovaries. Estradiol is available in various forms, including pills, patches, gels, and injections.
• Micronised Progesterone: Unlike synthetic progestins, micronised progesterone is bioidentical to the progesterone produced by the body. It is often used in combination with estrogen in hormone therapy for transgender women. Micronised progesterone is available in oral capsule form.
• Testosterone Cypionate or Testosterone Enanthate: These are injectable forms of testosterone used in masculinising hormone therapy for transgender men and non-binary individuals assigned female at birth. They are bioidentical to the testosterone produced by the testes.
• Testosterone Gel or Patches: These transdermal forms of testosterone offer an alternative to injections and are also bioidentical. They are applied to the skin and absorbed into the body.

Benefits of Bioidentical Hormones

• Chemical Structure: Being identical to endogenous hormones, bioidentical hormones are often well-tolerated and may have fewer side effects.
• Customisability: They can be customised in compounding pharmacies to suit individual needs, allowing for personalised treatment plans.
• Potential for Natural Metabolism: Their identical structure to natural hormones can be beneficial in how the body processes and metabolises them.

Considerations and Safety

While bioidentical hormones are often marketed as being ‘natural’ and ‘safer’, it’s important to note:

• Regulation: Not all bioidentical hormones are approved by health regulatory agencies like the FDA and MHRA. The compounded forms, in particular, are not regulated.
• Evidence and Research: There is a need for more extensive research to definitively conclude the long-term effects and safety of bioidentical hormones in comparison to conventional hormone therapies.
• Medical Supervision: Like all hormone therapies, bioidentical hormone treatments should be undertaken under the guidance of a knowledgeable healthcare provider.

Conclusion

Bioidentical hormones represent an evolving frontier in gender-affirming care. Their identical nature to the body’s hormones offers potential benefits in terms of efficacy and tolerance. However, it is crucial to approach them with the same level of scrutiny and medical guidance as one would with any hormone therapy. As research progresses, bioidentical hormones may offer more tailored and effective options for those seeking gender-affirming treatments.