This blood test measures the blood levels of the fractions (or isoenzymes) of the enzyme lactic dehydrogenase, also called LDH.
A doctor may order this test if he or she suspects tissue damage in the body.
In order to measure the amounts of LDH isoenzymes in the blood, a blood sample is taken from a vein on the forearm or hand. First, the skin over the vein is cleaned with an antiseptic. Next, a rubber tube is tied around the upper arm to enlarge the veins in the lower arm. A fine needle is gently inserted into a vein, and the tourniquet is removed. Blood flows from the vein through the needle and is collected in a syringe or vial to be tested in the lab. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.
No preparation is normally required for this test.
Normal levels of LDH are between 115 and 225 IU/L (international units per liter). Abnormally high levels of LDH may indicate: heart attack, or heart muscle damage from a blockage in a heart arteryhemolytic anemia, a condition in which red blood cells are destroyedinfectious mononucleosis, an infection caused by a virus called the Epstein-Barr virusintestinal damageliver disease, such as cirrhosislow blood pressurelung damagemuscle injurynew abnormal tissue formationpancreatitis, or inflammation of the pancreasstroke, or damage to the brain caused by a lack of oxygen