|See Also||Lab Tests|
Lactate dehydrogenase, also known as lactic dehydrogenase (LDH) is an intracellular enzyme used to support the diagnosis of injury or disease involving the heart, liver, red blood cells (RBCs), kidneys, skeletal muscle, brain, and lungs., 
- Since LDH is widely distributed through the body, the total LDH is not a specific indicator of any one disease or indicative of injury to any one organ.
- When disease or injury affects the cells containing LDH, the cells lyse and LDH is spilled into the bloodstream where it is identified in higher than normal levels.
- Five separate fractions (isoenzymes) make up the total LDH; LDH-1 comes mainly from the heart; LDH-2 comes primarily from the reticuloendothelial system; LDH-3 comes from the lungs and other tissues; LDH-4 comes from the kidney, placenta, and pancreas; and LDH-5 comes mainly from the liver and striated muscle.
- No fasting is required
- Factors which can cause increased levels:
- Hemolysis of blood, strenuous exercise
- Drugs: alcohol, anesthetics, aspirin, clofibrate, fluorides, mithramycin, narcotics, and procainamide
- Factors which can cause decreased levels:
- Drugs: ascorbic acid
High levels indicate:
- Myocardial infarction (MI)
- Pulmonary disease (e.g. embolism, infarction, pneumonia, CHF)
- Hepatic disease (e.g. hemolytic or megaloblastic anemia, RBC destruction from prosthetic heart valves)
- Skeletal muscle disease and injury (e.g. muscular dystrophy, recent strenuous exercises, muscular trauma)
- Renal parenchymal disease
- Intestinal ischemia and infarction
- Neoplastic states
- Testicular tumors
- Lymphoma and other reticuloendothelial system (RES) tumors
- Advanced solid tumor malignancies
- Diffuse disease or injury (e.g. heat stroke, collagen disease, shock, hypotension)
Low levels indicate:
- Not significant
- Aspartate aminotransferase (AST), Gamma-glutamyl transpeptidase (GGTP), Alkaline Phosphatase, 5'-Nucleotidase, Creatine Kinase (CK), Alanine aminotransferase (ALT), Leucine aminopeptidase (LAP), Troponin, Myoglobin, Liver Function Tests, CSF Analysis, Body Fluid Analysis, Tumor Markers
- Pagana Kathleen D, Pagana Timothy J (2006) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby.
- Weatherby Dicken, Ferguson Scott (2002) Blood Chemistry and CBC Analysis: Clinical Laboratory Testing from a Functional Perspective, Bear Mountain.