The causes of high lactate dehydrogenase in children mainly include the following aspects. First of all, due to the symptoms caused by children with myocarditis, myocarditis will cause the blood lactate dehydrogenase elevation, and often have creatine kinase isoenzyme elevation, and often accompanied by palpitations, chest tightness, pallor and other symptoms. Secondly, due to the symptoms caused by hepatitis in children, hepatitis will cause liver function damage, which will not only cause high lactate dehydrogenase, but also cause the elevation of glutamic oxaloacetic transaminase and glutamic alanine aminotransaminase, and need timely liver-protecting treatments, such as the application of MENENA.