LDH (Lactate dehydrogenase) is an enzyme in your body that plays a role in carbohydrate metabolism. It plays a role in the process required to convert glucose (sugar) from the food you eat into energy for the cells. Highest levels of LDH are present in muscle, liver, kidney & red blood cells. When body tissues are damaged due to chronic or acute disease, LDH is released into the blood & levels rise. This test is used to check if you have tissue damage; to monitor increased red blood cell breakdown as in anemias; to assess severity of certain types of cancer.