Human Lactate Dehydrogenase (LDH) Assay
When disease or injury affects tissues, the cells release LDH into the loodstream, where it is identified in higher than normal levels. Therefore, LDH is most often measured to evaluate the presence of tissue or cell damage.
The LDH assay is a non-radioactive colorimetric kinetic determination based on the reduction of the tetrazolium salt MTT, in an NADH-coupled enzymatic reaction, to a reduced form of MTT which exhibits an absorption maximum at 565 nm. The intensity of the purple color formed is directly proportional to the LDH enzyme activity in fresh or frozen plasma, serum, tissue extracts, or cell lysates. The detection range of the assay is 2-200 IU/L. Unit definition: 1 Unit (IU) of LDH will catalyze the conversion of 1 µmole of lactate to pyruvate per min at pH 8.2. Normal human LDH activity in serum is 41 IU/L. This assay is for research use only, not for diagnostic or therapeutic procedures.