What is the main source of lactate dehydrogenase (LD-1 and LD-2) in the bloodstream?

Lactate dehydrogenase (LDH) is an enzyme that plays a key role in the conversion of lactate to pyruvate during anaerobic metabolism. LDH exists in several isoenzymes, with LD-1 and LD-2 being primarily found in heart and red blood cells.

The main source of LD-1 and LD-2 in the bloodstream is red blood cells. These isoenzymes are released into the circulation when red blood cells are damaged or destroyed, which can occur in conditions such as hemolysis or certain types of anemia. Thus, elevated levels of LDH, particularly LD-1 and LD-2, can indicate issues related to red blood cell integrity or certain diseases affecting the heart.

Understanding the cellular origins of different LDH isoenzymes is important in clinical diagnostics. It allows healthcare professionals to interpret LDH levels in the context of tissue damage or disease processes, such as myocardial infarction, in which LD-1 levels tend to rise due to the release of the enzyme from damaged heart tissue.