Displaying 6 results of Creatinine Stable Isotopes Creatinine Stable Isotopes are non-radioactive isotopes of creatinine, a waste product of muscle metabolism that is excreted in urine. These isotopes are used in medical research to study kidney function and to develop accurate diagnostic tests for kidney disease. By introducing a known amount of stable isotopes into the body, researchers can track the metabolism and elimination of creatinine, providing valuable insights into kidney function.