simplify There is a direct and well-understood relationship between creatine monohydrate ingested as a nutritional supplement and the levels of creatinine found in the blood. To understand this, let's first clarify how these two molecules are related in the human body. ### How Creatine and Creatinine are Related in the Human Body **Creatine:** * **Function:** Creatine is a naturally occurring nitrogenous organic acid that plays a critical role in providing energy for muscle contractions, particularly during short bursts of high-intensity activity. * **Production:** It's primarily synthesized in the liver, kidneys, and pancreas from the amino acids arginine, glycine, and methionine. It can also be obtained through dietary sources, mainly meat and fish. * **Storage:** Approximately 95% of the body's creatine is stored in skeletal muscles, primarily as phosphocreatine (PCr). PCr acts as a rapid energy reserve, quickly regenerating adenosine triphosphate (ATP), the primary energy currency of cells. * **Role in Exercise:** During intense exercise, PCr donates a phosphate group to ADP (adenosine diphosphate) to quickly reform ATP, allowing muscles to sustain high-power output for longer periods. **Creatinine:** * **Function:** Creatinine is a waste product formed from the non-enzymatic breakdown of creatine and phosphocreatine in muscle tissue. It has no known physiological function. * **Formation:** Approximately 1-2% of the body's creatine and phosphocreatine stores are sponta