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Precautionary principle paradox
Endocrinological concept for the dichotomy between standard hormone care (strict precautionary regimen since WHI 2002) and cross-sex hormone treatment (no comparable threshold).
Definition
The precautionary principle paradox refers to the fact that the strict precautionary regimen that has dominated mainstream endocrinology since the Women's Health Initiative study of 2002 is not consistently applied to cross-sex hormone treatment — even though the risks associated with that treatment are logically greater, not smaller.
The paradox in one question
Ask a doctor this question: why are you so cautious with testosterone for a 55-year-old man with a proven deficiency, while you prescribe testosterone without much hesitation to a healthy 18-year-old woman who wants to masculinize her body? It is a question that is rarely asked aloud, but one that casts the entire field of gender care in a different light.
Regular restraint since WHI 2002
Regarding hormone replacement therapy within the same sex, medicine applies strict rules: only in cases of proven deficiency (hypogonadism, severe menopausal symptoms), the lowest effective dose, the shortest possible treatment duration, periodic monitoring of blood values, prostate, breast tissue, and liver, and continuous assessment of thrombosis, stroke, cancer, and cardiovascular risks. The turning point was the Women's Health Initiative study from 2002: hormone replacement therapy in women caused more breast cancer and cardiovascular disease than previously assumed. Since then, the motto has been: prescribing with restraint, on clear indication, with regular evaluation.
The gender care exception
In gender treatment, the same hormones — often in much higher dosages — are prescribed to people without an underlying endocrine abnormality:
- A biological woman develops male testosterone levels, sometimes 10 to 20 times her natural level.
- A biological male receives female estrogen levels, combined with suppression of his own testosterone production.
- Often via an "informed consent" model, sometimes after just one conversation.
- Long-term effects are poorly studied — the Cass Review (NHS, 2024) called the evidence base "remarkably weak".
- In minors, natural puberty is first suppressed — a procedure that is not performed on healthy children in any other medical context.
Working with or against the body
Supplementing same-sex hormones means supporting the body in something it was built for. Receptors, feedback systems, enzymes, and tissues are attuned to this hormone. If you stop the treatment, the body returns to its natural state. The risks are primarily a matter of dosage and pre-existing conditions.
Administering cross-sex hormones means the opposite: exposing the body to a hormone it was not designed for, in amounts that far exceed natural levels. At the same time, the body's own hormone production must be suppressed—with anti-androgens or GnRH agonists. You are working against the cellular architecture of every tissue: bones, heart, muscles, brain, liver. Many effects are irreversible.
The numbers tell the same story.
- Thrombosis and stroke — estrogen in biological men increases the risk to ~5× (Getahun 2018).
- Cardiovascular disease — testosterone in biological women increases cardiovascular events (Note 2019).
- Osteoporosis — especially when puberty blockers preceded the treatment.
- Infertility — often permanent.
- Cancer risk — only now coming into view because the first large cohorts have been treated long enough.
A 55-year-old man receiving testosterone for a proven deficiency remains within physiological ranges. A biological woman receiving testosterone for transition is at male levels — even though her body was never designed for that. That is a fundamentally different risk profile, not a gradual difference.
The linguistic problem
"Gender-affirming care" is a euphemism. Literally, "affirming the sex" would mean: acknowledging and supporting the biological sex. In practice, however, it means the exact opposite—rebuilding the body towards the other sex.
International reconsideration
The Cass Review (NHS, 2024), the Karolinska stop in Sweden (2021), the Finnish review (Palveluvalikoima 2020), and the Pathways Trial of King's College London (2025) all point in the same direction: the medical standard applicable to routine endocrinology is not consistently applied to gender treatment. First-line treatment for adolescents is shifting towards a comorbidity-first approach and exploratory therapy; hormonal and surgical interventions have become the exception, not the rule.
The unanswered question
A biological body reacts the same way to a hormone, regardless of the reason for administration. The risks associated with cross-sex hormones are logically greater, not smaller. Yet the precautionary principle that has dominated conventional hormone care since 2002 is systematically ignored in gender care. The answer to that question is not medical but political-ideological — and that is precisely where the core of the international reconsideration currently underway lies.
Sources
- Rossouw JE et al. WHI: estrogen plus progestin. JAMA 2002;288(3):321-333.
- Cass H. Independent Review—Final Report. NHS England, April 2024.
- Getahun D et al. AnnIM 2018;169(4):205-213.
- Nota NM et al. Circulation 2019;139(11):1461-1462.
- Joseph T et al. JPEM 2019;32(10):1077-1081.
- Palveluvalikoima (Finland). COHERE, 2020.
- SBU/Karolinska, Sweden, 2021.
- Pathways Trial. King's College London, 2025.