Many descriptions have been used to explain hormones and hormone therapies.  They are often confusing and misleading.  Here are the most important terms.

Hormone Replacement Therapy (HRT)

This refers to treatment using the patented hormones manufactured and sold by pharmaceutical companies.  These have been the standard hormones that most medical doctors prescribe in their practices.  Examples are Prempro, Provera and Premphase.  The molecular structure of these hormones is purposely altered to be different from the hormones that your body makes naturally.  This makes them patentable and profitable for pharmaceutical companies.  Unfortunately, these small changes to hormone structure can result in significant changes in hormone function, resulting in unwanted and unexpected side effects.  Critics of HRT have termed them hormone-flavoured drugs or pseudohormones, and there are many studies that have shown HRT causes harm.  The most prominent study, the Women’s Health Initiative (WHI), was abruptly halted in 2002 because morbidity and mortality (illness and death) were significantly increased by taking HRT.

Bioidentical Hormone Replacement Therapy (BHRT)estradiol

This refers to treatment using bioidentical hormones.  Individual prescriptions specific to each patient’s requirements are compounded by pharmacists into creams, gels, suppositories and oral lozenges.  Treatment is unique to each patient.  While BHRT has been around for decades, it has only been in the last 10 years that it has become very popular.  Only a small percentage of doctors prescribe BHRT and they take additional medical education and training.

Natural Hormones

We all like to think that natural is best.  Natural hormones are the best hormones, but they are only made in your body.  You cannot squeeze a natural hormone out of a wild yam or a soybean.  Pharmaceutical companies cannot make a natural hormone; they can only make synthetic hormones.  All hormones, including BHRT hormones are synthetic.  The reason why proponents of BHRT incorrectly refer to them as natural is because their molecular structure is identical to the natural hormones your body makes.  This means that when you take them, your body reacts to them just as if they were your own hormones.  This is why BHRT is superior to HRT.

Synthetic Hormones

Synthetic is the term often used to describe the hormones that are used in conventional HRT.  Premarin and Provera are the hormones most commonly referred to as being synthetic.  The term is used to convey a sense that they are inferior to natural hormones.  While it is true that HRT hormones are inferior, it has nothing to do with the fact that they are synthetic.  Since natural hormones cannot be manufactured, all hormones are synthetic, including BHRT hormones.  They are all made from a substance called diosgenin that is extracted from soybeans and wild yams and then modified in the laboratory to create hormones.

Bioidentical Hormones

Bioidentical hormones have the identical molecular structure to the hormones that your body makes.  A more appropriate term might be ‘human-identical’ hormones.  Bioidentical hormones are the hormones used in BHRT.  These hormones are often mistakenly referred to as natural hormones.  In reality, they are synthetic and made by pharmaceutical companies.  They are, however, exact replicas of your natural hormones.  Your body recognizes them as perfect hormones and metabolizes them as if you had made them.  Bioidentical hormones have been manufactured for over 75 years and there is not one study that shows that they cause harm.  Since they are exact replicas of your natural hormones, they cannot be patented, thus making them unprofitable for pharmaceutical companies.


Progestins are progesterone-like patented drugs that mimic the hormone progesterone.  Provera (medroxyprogesterone acetate) is a progestin that has been a standard component of HRT for decades.  It has been mistakenly referred to as progesterone for so long that even physicians use the term Provera interchangeably with progesterone.  Progestins, however, are not progesterone.  Like progesterone, progestins help prevent the buildup of the uterine lining of women taking estrogen, but this is where the similarity ends.  Progestins cause a multitude of side effects including increased risk of birth defects and breast cancer.


Progesterone is an anti-estrogenic steroid hormone secreted by the ovaries and adrenal glands.  Natural progesterone, progesterone and bioidentical progesterone all refer to the hormone that is produced by your body and commonly used in BHRT.  Bioidentical progesterone has the same molecular structure as the progesterone your body makes.  Usually administered by cream or gel and sometimes by oral prescription, it is a perfect fit for all of the progesterone receptor sites in your body.  Unlike progestins, progesterone decreases the risk of breast cancer.


This is one of the common estrogens used in HRT.  Premarin is a unique set of horse estrogens derived from pregnant mare’s urine.  Many people think Premarin is a natural hormone because it is composed of estrogens derived from horse urine.  While horse urine does occur in nature, it’s not natural to the human body.  It’s bioidentical for horses, but it’s not bioidentical for humans.  The Women’s Health Initiative study found that Premarin was responsible for increased risk of cancer and cardiovascular disease.

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