Lactic Acid Dehydrogenase (LD)
| Lactic Acid Dehydrogenase (LD) | | | |
| Number | | 001115 |
| CPT | | 83615 |
| Synonyms | | LD ; LDH |
| Specimen | | Serum |
| Volume | | 1 mL |
| Minimum Volume | | 0.5 mL |
| Container | | Red-top tube or gel-barrier tube |
| Collection | | Separate serum from cells within 45 minutes of collection. |
| Storage Instructions | | Maintain specimen at room temperature. |
| Causes for Rejection | | Excessive hemolysis; improper labeling |
| Reference Interval | | 100-250 IU/L |
| Use | | Causes of high LD: Neoplastic states* (especially with high alkaline phosphatase, very high total LD, and isomorphic pattern of LD isoenzymes); hypoxic cardiorespiratory diseases; hemolytic anemia*; megaloblastic anemias*, including pernicious anemia* (levels may be >2000 units/L and LD isoenzymes reveal LD1:LD2 flip); infectious mononucleosis*; inflammation; hypothyroidism (some cases*); myocardial infarct: LD begins to rise about 12 hours after infarct and usually returns to normal after CK (CPK) and AST (SGOT), isoenzymes usually most useful 48 hours from onset to reveal LD1:LD2 inversion*; pulmonary infarct (rarely, triad of LD, bilirubin, AST increases occurs); other lung diseases. Diseases of liver*, including cirrhosis. Total LD in cirrhosis is usually not greatly increased. In acute viral hepatitis, LD is not greatly elevated and AST is usually three or more times higher (in relation to the upper limit of normal) than LD; chronic alcoholism is usually associated with some combination of high MCV (mean corpuscular volume), triglyceride, alkaline phosphatase, AST (SGOT), ALT (SGPT), GGT, bilirubin, and low folate*. Renal infarct* - high LD, out of proportion to AST and alkaline phosphatase;1 seizures, other CNS diseases; acute pancreatitis; collagen diseases; excessive destruction of cells*; fracture, other trauma, including head trauma, muscle damage; muscular dystrophy; focal necrosis; shock, hypotension; intestinal obstruction. *LD isoenzymes may be useful. Other causes of increased LD include specimen tube artifact, such as serum contact with clot or exposure to heat. Chemistry profile with very high LD and no glucose may relate to unseparated serum and cells in a tube at room temperature or higher. Since LD is found in virtually every tissue in the body, the diagnostic value of an elevated level is limited. |
| Limitations | | Hemolysis elevates LD results; oxalate inhibits LD; ascorbic acid can decrease LD values. |
| Methodology | | Kinetic |
| Additional Information | | In infectious mononucleosis, LD is usually more elevated than AST, and there is usually an isomorphic pattern of LD isoenzymes. In viral hepatitis, by contrast, AST and ALT (the transaminases) are much more increased than is LD, about three or more times higher than total LD, and LD5 is high. The differential diagnosis of acute infarct of myocardium includes pericarditis and angina, entities in which enzymes are usually not substantially increased. Bovine or porcine heparin therapy can cause increases of AST, ALT, and LD, with elevated LD hepatic fractions.2 |
| Footnotes | | - Winzelberg GG, Hull JD, Agar JW, et al, “Elevation of Serum Lactate Dehydrogenase Levels in Renal Infarction,” JAMA, 1979, 242(3):268-9.
- Dukes GE Jr, Sanders SW, Russo J Jr, et al, “Transaminase Elevations in Patients Receiving Bovine or Porcine Heparin,” Ann Intern Med, 1984, 100(5):646-50
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