Bioidentical hormone replacement therapy (BHRT), also known as bioidentical hormone therapy or natural hormone therapy, is the use of hormones that are identical on a molecular level with endogenous hormones in hormone replacement therapy. It may also be combined with blood and saliva testing of hormone levels, and the use of pharmacy compounding to obtain hormones in an effort to reach a targeted level of hormones in the body. A number of claims by some proponents of bioidentical hormone replacement therapy have not been definitively established through scientific testing. Specific hormones used in BHT include estrone, estradiol, progesterone (which are available both in FDA-approved manufactured products and as pharmacy-compounded products), testosterone, dehydroepiandrosterone (DHEA) (both testosterone and DHEA have some stringent limits placed on their availability and approval in Canada and the United States), and estriol (which is available in Europe but is not approved in Canada and the United States).