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. 
One of the main functions of the circulatory system is to pump blood throughout the body so that oxygen and nutrients can reach the tissues. The heart works as the pump, and is it actually considered a “double pump”, since the right side distributes blood towards the lungs for oxygenation, while the left side forces blood through the aorta so that oxygenated blood can circulate to the tissues. Blood vessels within the circulatory system include an arterial system and a venous system. Arteries carry blood away from the heart and towards tissues, while the venous system carries deoxygenated blood back to the heart.
steroid ster·oid (stěr'oid', stēr'-)
Any of numerous naturally occurring or synthetic fat-soluble organic compounds having as a basis 17 carbon atoms arranged in four rings and including the sterols and bile acids, adrenocortical and sex hormones, certain natural drugs such as digitalis compounds, and the precursors of certain vitamins. Also called steroid hormone . adj. ste·roid·al (stĭ-roid', stě-)
Relating to or characteristic of steroids or steroid hormones.