Target: Urine Creatinine
Product Type: Detection Kits
Trademark: StressXpress®
Detection Method: Colorimetric Assay
Assay Type: Direct Quantitative Assay
Utility: Detection kit used to quantitatively measure creatinine in samples.
Precision: Intra Assay Precision: Three human urine samples were diluted 1:20 with deionized water and run in replicates of 20 in an assay. The mean and precision of the calculated creatinine concentrations were:Sample 1- 1174.3 pg/mL, 6% CVSample 2- 475.9 pg/mL, 5.6% CVSample 3- 177.4 pg/mL, 14.7% CVInter Assay Precision: Three human urine samples were diluted 1:20 with deionized water and run in duplicates in 20 assays run over five days by three operators. The mean and precision of the calculated creatinine concentrations were:Sample 1- 1188.1 pg/mL, 7.2% CVSample 2- 508.7 pg/mL, 6.3% CVSample 3- 199.7 pg/mL, 10.9% CV
Sample Type(s): Urine
Number of Samples: 88 samples in duplicate
Sensitivity: 0.032 mg/dl
Assay Range: 0.3125- 20 mg/dl
Scientific Background: Creatinine (2-amino-1-methyl-5H-imadazol-4-one) is a metabolite of phosphocreatine (p-creatine), a molecule used as a store for high-energy phosphate that can be utilized by tissues for the production of ATP (1). Creatine either comes from the diet or synthesized from the amino acids arginine, glycine, and methionine. This occurs in the kidneys and liver, although other organ systems may be involved and species-specific differences may exist (2). Creatine and p-creatine are converted non-enzymatically to the metabolite creatinine, which diffuses into the blood and is excreted by the kidneys. In vivo, this conversion appears to be irreversible and in vitro it is favored by higher temperatures and lower pH2. Creatinine forms spontaneously from p-creatine (3). Under normal conditions, its formation occurs at a rate that is relatively constant and as intra-individual variation is <15% from day to day, creatinine is a useful tool for normalizing the levels of other molecules found in urine. Additionally altered creatinine levels may be associated with other conditions that result in decreased renal blood flow such as diabetes and cardiovascular disease (4-6).
References: 1. Wallimann, T. et al., Biochem. J., 2000, 281, 21-40.2. Wyss, M. and Kaddurah-Daouk, R., Physiol. Rev., 2000, 80, 1107-1213.3. Raja Iyengar, M. et al., J. Biol. Chem, 1985, 260, 7562-7567.4. Manjunath, G. et al., Postgrad. Med. 2001, 110, 55-62.5. Gross, J.L. et al., Diabetes Care, 2005, 28, 164-176.6. Anavekar, N.S. et al., New Engl. J. Med., 2004, 351, 1285-1295.
Field of Use: Not for use in humans. Not for use in diagnostics or therapeutics. For in vitro research use only.
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