Creatinine is a metabolite waste product of phospho-Creatine (p-Creatine), a molecule used as a store for high-energy phosphate that can be utilized by muscles and other tissues for the production of ATP. Dietary intake andde novo synthesis from the amino acids arginine, glycine, and methioninein the kidney and liver are the primary sources of Creatine. Creatine and p-Creatine are converted non-enzymatically to the metabolite Creatinine, which diffuses into the blood, is filtered through the kidneys, and is then secreted into urine. In vivo, this conversion appears to be irreversible and in vitro it is favored by higher temperatures and lower pH. Some Creatinine may form via p-Creatinine as well. Under normal conditions, Creatinine's formation occurs at a rate that is relatively constant. For instance, in humans approximately 2% of the Creatine/p-Creatine pool is converted to Creatinine daily. This predictability makes Creatinine a useful tool for normalizing the levels of other molecules found in urine. In addition, altered Creatinine levels can be used as an indicator of kidney dysfunction, or may be associated with other conditions that result in decreased renal blood flow. Some examples include diabetes and cardiovascular disease. The RayBio^® Creatinine assay is a 30 minute chemical analysis designed to measure Creatinine in urine.

The entire kit should be stored at 2-8 °C for up to 6 months from the date of shipment. Do not use past kit expiration date.