Acetoacetate (AcAc) is the simplest β-keto acid and is one of the three ketone bodies. Acetoacetate is produced through condensation of two molecules of acetyl-CoA in liver mitochondria. Acetoacetate can be decarboxylated to produce acetone (CH₃)₂CO or enzymatically reduced to 3-β-hydroxybutyrate (β-HB). Ketone bodies (β-HB: 78%; AcAc: 20%; (CH₃)₂CO: 2%) are primarily used as an alternative energy source when glucose cannot be delivered to the system. Excessive concentration of ketone bodies is found in patients with severe starvation, alcoholism or Type I diabetes. Using the traditional method, AcAc levels can be qualitatively detected using dipsticks that use sodium nitroferricyanide as a chromophore. The Acetoacetate Colorimetric Assay Kit provides a specific and sensitive way for detection of AcAc levels in various body fluids based on colorimetric method. The kit modified the principle of the traditional method. In the assay, AcAc reacts with a substrate to yield a colored product that can be measured at 550 nm. The assay is specific for AcAc and does not detect β-HB. The kit can detect as low as 25 µM AcAc in human blood, urine and other body fluids.