Bio-identical hormone therapy uses hormones that are molecularly identical to the hormones naturally produced in our bodies. Some of these medications are sold at commercial pharmacies and others are compounded at specialized pharmacies. Pharmaceutical companies cannot patent natural or bio-identical hormones, so their products are synthetic and are not the same structurally as the hormones we have in our bodies. Synthetic hormones clinically act very different from bio-identical hormones. Bio-identical hormones include thyroid, estrogen, progesterone, testosterone, growth hormone, melatonin, vitamin D and DHEA.