Lactate dehydrogenase is not always elevated in lymphoma, and elevation suggests a poor prognosis, and the diagnosis of lymphoma needs to be combined with other ancillary tests. Lactate dehydrogenase is a glycolytic enzyme, which can catalyze anabolic glycolysis and gluconeogenesis, and is widely found in human tissues. Generally, the serum level of lymphoma patients will be significantly elevated, which is related to the rapid proliferation of lymphoma itself. The more malignant the lymphoma, the faster the proliferation, the higher the metabolic activity, the more and more severe the metastatic involvement of tissues and organs, the greater the tumor load, the higher the level of lactate dehydrogenase produced. Lactate dehydrogenase is one of the indicators to determine the prognosis of lymphoma. A small number of lymphomas with low malignancy and early stage may show no elevation of lactate dehydrogenase. Lactate dehydrogenase has a high sensitivity but poor specificity, and can also be seen in cardiac infarction, pulmonary embolism, acute hepatitis, etc. It is recommended to seek medical attention, and improve the lymph node aspiration biopsy, if necessary, to clarify the diagnosis.