Myostatin levels are effectively decreased by creatine supplementation. However, subjects have shown the same muscle creatine levels after using creatine supplements. Creatinine is the product of muscle creatine catabolism. They include molecules such as adenosine triphosphate (ATP), glycogen and creatine phosphate. Some studies suggest that total muscle creatine is significantly lower in vegetarians than non-vegetarians. Many molecules such as potassium, creatine kinase, phosphate, and myoglobin are released into circulation. Examples of guanidines are arginine, triazabicyclodecene, saxitoxin, and creatine. Clinically, there are three distinct disorders of creatine metabolism. They also excrete creatine, rather than creatinine like mammals. Markers of myocardial damage (troponin or creatine kinase cardiac isoenzymes) are elevated. Ryan DeLuca in 1997, to capitalize on the rising popularity of creatine supplements. Commonly used blood tests include troponin and less often creatine kinase MB. The six that were approved are caffeine, ephedrine, energy drinks, modafinil, creatine, and blood-loading. Creatine synthesis primarily occurs in the liver and kidneys. In chemical terms, creatinine is a spontaneously formed cyclic derivative of creatine.