Synthetic hormones are generally lab created, standardized pharmaceutical hormones.  The standardized dosing makes it easier to start a patient on hormones and easier to conduct controlled studies on to determine side effects that might occur.  Since every patient’s body is different it can make trying to dose these hormones hard because the synthetic hormones may worsen the disorder that is being treated or not effectively treat the disorder

Bio-identical hormones are augmented in a lab from a natural source such as the steroid structure from Dioscorea villosa (Wild Yam) or from endocrine tissue from an animal that produces hormones similar to human hormones.  Since the steroid structure is still chemically altered it is considered synthetic, but is also considered more “natural”.  Since bio-identical hormones are not standardize, dosing can be customized to the individual person.

The best way to think about the difference between fully synthetic hormones and bio-identical is to consider their structures in relation to hands.  The right and left hand look similar to one another in most aspects – five fingers, general size, and color.  Synthetic hormones look the same as the hormones produced in the body, just like your two hands, but are many times the mirror image of the other so when you lay them over each other the synthetic hormone looks backwards.  This requires the body to modify the synthetic hormone into something that it can use.  Sometimes this is ok and at other times it is not, creating side effects or the negative effects that can occur with that hormone.

The bio-identical hormones look exactly like the natural occurring hormones in the body.  When the bio-identical hormone is laid over the natural occurring hormone they match up completely so the body does not need to augment the bio-identical hormone at all limiting the side effects and negative effects that can occur.  An example of this would be with the most prescribed bio-identical hormones – estradiol and progesterone.  These bio-identical hormones look like the natural occurring estradiol and progesterone in the body.  

There are three forms of naturally occurring estrogen produced in the body – estradiol, estrone and estriol.  Multiple studies have shown that estradiol is a protective and balancing estrogen whereas estrone has detrimental and negative effects on the body.  Estriol is a lesser protective estrogen but does not have a very strong role in the body.  Estradiol has been shown to be protective against many cancers, osteoporosis, cardiovascular disease, and nerve degeneration.  Estrone is responsible for the negative effects of estrogen such as breast cancer, cardiovascular disease (heart attacks, vasculitis, and strokes) and nerve degeneration.

The bio-identical hormone of estradiol has an increased likelihood to stay as estradiol and not contribute to an increase in estrone, thus decreasing the risk of taking hormone replacement therapy.  A synthetic hormone has a fifty-fifty chance of being converted into estrone, thus increasing the risk of taking synthetic hormone replacement therapy.   

It is important to note that some drug companies also make estrogens and progesterone from plants like soy and yams in standardized extracts.  Some of these are also chemically identical to the hormones made by your body and some are not. One difference between the natural hormones prepared by a compounding pharmacist and those made by a drug company is that the compounded natural hormones are not regulated and approved by the U.S. Food and Drug Administration (FDA).  Hormones made by drug companies are regulated and approved by the FDA.