Lactate dehydrogenase, better known as LDH or LD, is an enzyme found in nearly all body tissues and organs: the muscles (including the heart), liver, lungs, red and white blood cells, and even the bacteria that infect us.
High LDH levels in the blood indicate that the cells in one of the body tissues are being damaged or destroyed and are releasing LDH into the bloodstream. But an LDL test cannot be used to identify which tissue or organ is affected. Abnormal LDH levels must be interpreted through other tests and clinical indications.
High LDH levels can be seen when a large number of red blood cells have been damaged (as in hemolytic or pernicious anemia) or in the presence of severe infections (mononucleosis, meningitis, encephalitis, HIV), septicemia, acute illnesses (liver, kidneys, muscles, lungs, intestine or pancreas), bone fractures and certain cancers (testicular or ovarian cancer, lymphoma, and others). In addition, the success of certain cancer treatments can be confirmed by monitoring LDH blood levels.