We accept
The belief that bioidentical hormones are inherently safer than synthetic hormones is one of the most debated and, often, misinterpreted topics in menopause medicine. For anyone considering hormone replacement therapy (HRT), it is crucial to have a detailed and honest analysis that separates the myth from the scientific evidence.
The truth is that the safety of HRT does not depend so much on whether a hormone is bioidentical or synthetic, but on more important factors such as the route of administration, the type of progesterone used and the moment of initiation of treatment.
La Diferencia Clave: Molecular Structure, No “Origen”
To understand security, we first have to clarify the difference:
Bioidentical Hormones: They have a molecular structure identical to the hormones that the human body produces naturally (such as estradiol and progesterone). Although it is manufactured in laboratories from plant precursors, its final structure is an exact replica of endogenous hormones.
Synthetic Hormones: They have a similar, but not identical, molecular structure. They were designed in laboratories to imitate the effects of human hormones, but their slightly different form could have different consequences in the body.
The myth of the “inherent safety” of bioidenticals is based on the logic that “perfect shoes” are better for the body. However, science has demonstrated that security is a much more complex topic than a simple “yes” or “no”.
Factors that Really Define the Safety of Hormone Therapy (Detailed Analysis)
Current scientific evidence has shifted the focus of the “bioidentical vs. synthetic” debate to factors that have a much more significant impact on the patient's risk profile.
Why: Estrogen administered orally (in tablets) is metabolized by the liver, which can increase the production of blood clotting factors. This process is known as the “hepatic first step”.
The Risk: This first hepatic step of oral estrogen is the one that has been associated with a greater risk of venous thromboembolism (blood clots in the deep veins, DVT) and stroke (cerebrovascular accident).
The Truth: Transdermal estrogen therapy (patches, gels, sprays) enters directly into the bloodstream, avoiding passage through the liver. Therefore, it is considered a significantly safer option to minimize cardiovascular risks, as it does not increase the risk of clots.
Analysis: Safety in this area is not linked to whether estrogen is bioidentical or synthetic, but to how it is administered. The majority of transdermal estrogens available in Spain are bioidentical, which has led to the erroneous perception that their safety is due to their “bioidentical” nature rather than the route of administration.
El Why: For women who still have their uterus, HRT must combine estrogen and progesterone. Progesterone is vital to protect the uterine lining from excessive growth that could lead to uterine cancer.
The Evidence: Several studies have suggested that the use of micronized natural progesterone (a bioidentical hormone) in combined therapy has a more favorable safety profile than some synthetic progestins (such as medroxyprogesterone acetate) at a risk of long-term breast cancer.
The Truth: Security in this case is linked to the specific molecule. Micronized progesterone has a similar profile to the body, although synthetic progestogens have structures that do not exist naturally and can have different effects.
The Why: The risk of cardiovascular complications is strongly linked to age.
The Evidence: The risk is significantly lower in women who start HRT during perimenopause or shortly after menopause (before 60 years or within 10 years after its start). Starting HRT many years after menopause (as occurred in the WHI cohort) is associated with greater risk.
The Truth: This temporal factor is, for many doctors, the most important determinant of safety, even surpassing the distinction between bioidentical and synthetic hormones.
El Riesgo: In the United States, some bioidentical hormones are prepared in master formulating pharmacies (“compounding pharmacies”). These preparations have not been subjected to the same clinical trials as approved medications and can have variable and inconsistent dosages, which increases the risk for the patient.
La Verdad en España: In Spain, the AEMPS (Agencia Española de Medicamentos y Productos Sanitarios) strictly regulates medicines. Bioidentical hormones that are commonly prescribed, such as estradiol in gels/patches and oral micronized progesterone, are proven and standardized pharmaceutical products. A qualified doctor in Spain will always prescribe regulated products.
Conclusion: A Personalized Approach Under Medical Supervision
The answer to whether bioidentical hormones are “safer” is more nuanced. Scientific evidence suggests that, in the context of a well-chosen therapy, certain types of bioidentical hormones have a more favorable safety profile for specific risks. For example, bioidentical transdermal estrogen is safer for the heart than oral estrogen, and micronized progesterone is preferable to some synthetic progestins for breast cancer.
However, safety is not an inherent attribute of the “bioidentical” label. The key is in a personalized approach and a detailed and honest conversation with your specialist doctor. It will evaluate your symptoms, your clinical history, your individual risk factors (such as the moment of menopause) and your preferences for designing an individualized treatment plan, selecting the therapy, route of administration and doses that are most appropriate and safe for use.
Disclaimer: The information provided in this document is for educational purposes and should not be considered as medical advice. Always consult a qualified health professional before making any decision about your treatment.
| Monday | 09:00 - 17:00 |
| Tuesday | 09:00 - 17:00 |
| Wednesday | 09:00 - 17:00 |
| Thursday | 09:00 - 17:00 |
| Friday | 09:00 - 17:00 |
| Saturday | 09:00 - 17:00 |
| Sunday | Closed |