The Creatinine Extended Range R1 & R2 Reagents quantitatively determine the creatinine concentration in urine samples. This assay is for use on automated chemistry analyzers. The assay exhibits a linear range up to 600 mg/dL on many automated chemistry analyzers. It is well known that a 24 hour urine collection can be utilized to determine drug consumption by an individual. This determination is very beneficial for current management of pain medications. It is also well known that random urine samples can be substitued for 24 hour collections and “normalized” using creatinine values. The extended linear range of this assay eliminates the need to dilute urines outside of the linear range of typical Creatinine Assays (0 to 300 mg/dL), thereby saving time. The Creatinine Extended Assay is a modified Jaffe method in which the specimen reacts with hydroxide and picric acid to yield a colored complex read spectrophotometrically at a wavelength of 505 nm. The color intensity is proportional to the concentration of creatinine present. Stability and Storage: Unopened and opened bottles are stable until expiration date noted on bottle when stored tightly capped at room temperature. If left on instrument they should be capped or taken off the instrument and capped.