The ‘Two-Pin’ technique increases sanitation for multiple dose vial users. They draw with the first pin, and then shoot/inject into the body with a new one. This procedure prevents any residual contaminants that may have remained on the drawing pin from being transferred into the body via the injection site. It also makes injection less painful since the drawing needle is necessarily dulled during passage through the rubber stopper atop the vial. A dulled needle increases injection pain because it doesn’t pierce the body as cleanly as an unused one. The protocol below is followed by AAS users who draw from multiple dose vials, but steps 4 - 8 are routinely disregarded by those users who draw from ampoules (also called ampules) and sachets.
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.