Lactate dehydrogenase (LD)

Lactate dehydrogenase (LD) is an enzyme that is found in almost all of the body's cells, but only a small amount of it is usually detectable in the blood. LD is released from the cells into the bloodstream when cells are damaged or destroyed. Because of this, the LD test can be used as a general marker of injury to cells. Although there is some overlap, each of the five LD isoenzymes tends to be concentrated in specific body tissues. In general, the isoenzyme locations are as follows: • LD1: Heart, red blood cells, kidney • LD2: Heart, red blood cells, kidney (lesser amounts than LD1) • LD3: Lungs and other tissues • LD4: White blood cells, lymph nodes, muscle, liver (lesser amounts than LD5) • LD5: Liver, skeletal muscle Changes of LD isoenzymes periodically measured following onset of chest pain, studying the relationships of the anodic fractions, provide important information for the differential diagnosis of acute infarct of myocardium. The differential diagnosis of certain other d