to promote BHT suggests that rather than basing hormone doses on saliva results, practitioners are adjusting dosage based on symptoms. Different bioidentical preparations result in mixtures with different strengths, and practitioners using compounded formulations may be unaware of the total dose of hormones their patients receive. In a 2001 test of compounded bioidentical hormone products, the FDA found that 10 out of 29 products failed their quality tests; nine out of ten failed potency tests (comparable rates for drug manufacturers were less than 2% and 0.13%, respectively). A 2006 test found potency levels ranging from 67.5% to 268.4% of the potency specified on the label; some samples were mixtures of different hormones with some being above, and others below, the specified potency. The failure of potency testing could be problematic and dangerous for progesterone products, where specific levels of progesterone are required to protect the endometrium against precancerous hyperplasia. Boothby, Doering, and Kipersztok summarize the issue as being a poor effort to apply principles of pharmacokinetics to achieve individualized dosing for drugs that do not require it. Saliva testing has not been shown to accurately measure blood-bound hormone levels. The FDA recommends the lowest dose of hormones that effectively relieve symptoms and does not recommend custom compounding, blood or saliva testing. Lack of evidence for claims Bioidentical hormones have been advertised, marketed and promoted as a risk-free panacea that is safer than standard HRT. Literature reviews by private practitioners who sell bioidentical preparations suggest benefits and advantages of BHT over its conventional counterpart, but there is skepticism over claims made about BHT; there is no peer-reviewed evidence that compounded bioidentical hormones are safer or more effective than FDA-approved formulations or that they carry less risk. The hormones are expected to carry the same risks as their conventional counterparts, while the risks of including estriol—a hormone normally produced in large amounts only in pregnant women—have not been studied. The United States FDA warned that claims about compounded BHT products are unsupported by medical evidence. Bioidentical hormones have been described as a form of marketing; the chief medical editor of Endocrine Today called compounded BHT a "marketing concept" with no scientific backing, and the FDA warned that pharmacies use these terms to imply that the drugs are natural and have the same effects as endogenous hormones. Other claims include compounded BHT's ability to prevent or treat conditions such as heart disease, stroke,