The normal standard values for lactate dehydrogenase are 104 to 245 U/L. Lactate dehydrogenase 300 is a mild elevation that needs to be determined in conjunction with other tests and medical history. Elevated lactate dehydrogenase is important in the diagnosis of certain cardiac and hepatic diseases and malignant tumors. Elevated lactate dehydrogenase is commonly seen in the following diseases: 1. Heart disease: such as acute myocardial infarction. 2. Liver diseases: such as hepatitis, fatty liver, cirrhosis, hepatocellular carcinoma and so on. 3. Malignant tumors: such as acute leukemia, gastric cancer, lung cancer, rectal cancer, bladder cancer, etc. 4. Other diseases: such as anemia, shock, malnutrition, etc. If lactate dehydrogenase is elevated, it is recommended to consult the hospital for a definite diagnosis after combining with medical history and other examinations.