Inexpensive, Accurate, and Stable Method to Quantitate Blood Alanine Aminotransferase (ALT) Levels

Alanine aminotransferase (ALT) levels are frequently determined in serum and plasma samples and are a primary measure to quantitate hepatocellular injury in rodents, humans, and other organisms. An accurate, reliable, and scalable assay is hence of central importance. Here, we describe a methodology that fulfills those requirements, and demonstrates an excellent performance similar to a commercial ALT kit, with a long stable performance over several subsequent runs. Further, anticoagulation of blood samples with ethylenediaminetetraacetic acid (EDTA) or heparin results in similar ALT concentrations with this assay, whereas no anticoagulation significantly increases ALT levels. Mild hemolysis does not significantly increase ALT levels; however, moderate to severe hemolysis does lead to higher ALT levels. The assay provides stable results over a wide range of associated triglyceride concentrations that can be expected in serum and plasma samples from rodents and humans with dyslipidemia. It also performs well in diluted samples with a reduction of ALT levels corresponding to the factor used to dilute the samples. The described ALT reagent is also very affordable, costing less than 1/80 of comparable commercial kits. Based on the characteristics above, this methodology is suitable for a broad spectrum of applications in mice and possibly humans, where ALT concentrations need to be determined.