LDH refers to lactate dehydrogenase, which is widely present in many tissues and cells in the body, most commonly in the heart and liver. When patients develop heart disease, including angina pectoris or myocardial infarction, lactate dehydrogenase will be significantly elevated, including other cardiac enzymes. Lactate dehydrogenase may also be elevated in patients with liver disease, such as hepatitis. Lactate dehydrogenase is also found in the body’s red and white blood cells, and is significantly elevated in patients with hemolytic anemia. Some malignant diseases of the hematological system, including acute leukemia and lymphoma, may also show elevated lactate dehydrogenase, which usually indicates a high tumor load in the patient’s body and should be treated with care to prevent tumor lysis syndrome.