Heavy consumption of the essential amino acid lysine (as indicated in the treatment of cold sores) has allegedly shown false positives in some and was cited by American shotputter C. J. Hunter as the reason for his positive test, though in 2004 he admitted to a federal grand jury that he had injected nandrolone.  A possible cause of incorrect urine test results is the presence of metabolites from other AAS, though modern urinalysis can usually determine the exact AAS used by analyzing the ratio of the two remaining nandrolone metabolites. As a result of the numerous overturned verdicts, the testing procedure was reviewed by UK Sport . On October 5, 2007, three-time Olympic gold medalist for track and field Marion Jones admitted to use of the drug, and was sentenced to six months in jail for lying to a federal grand jury in 2000. 
Drugs can be added and removed from this list by WADA annually, although not all of the banned substances are explicitly named. Caroline Hatton, PhD , a sports anti-doping science consultant, told in a Mar. 12, 2010 email that "A key concept in prohibited lists is that they avoid being finite. Instead of listing all banned drugs one by one, they list entire drug classes and name drugs merely as examples. This is to keep users who took designer drugs from claiming that they didn't break the rules because the drugs they took weren't listed."
Athletes, like all others, may have illnesses or conditions that require them to take particular medications. If the medication an athlete is required to take to treat an illness or condition happens to fall under the prohibited list, a therapeutic use exemption may give that athlete the authorization to take the needed medicine. Criteria for granting a therapeutic use exemption are 1.) The athlete would experience significant health problems without taking the prohibited substance or method, 2.) The therapeutic use of the substance would not produce significant enhancement of performance, and 3.) There is no reasonable therapeutic alternative to the use of the otherwise prohibited substance or method. Note hormone replacement therapy (HRT), . supplementing with prescribed testosterone in any form to raise testosterone levels due to natural decreases that occur with aging (even if to just elevate levels to within ‘normal’ ranges), is NOT considered a medicinal exception. Persons using HRT would not be eligible for WPA/NANBF/IPE competition.