Dehydrogenase (LDH)

Overview

Lactate dehydrogenase (LDH) is an intracellular enzyme that catalyzes the interconversion of lactate and pyruvate during anaerobic glycolysis and is present in many tissues, including heart, liver, muscle, kidney, lung, and red blood cells. Total LDH in blood reflects cell turnover and tissue injury rather than a single organ’s function. Elevated LDH levels occur in conditions associated with cell damage or hemolysis, such as myocardial infarction, liver disease, hemolytic anemia, malignancy, and severe infection, while low levels are rare and usually not clinically significant. LDH is clinically useful as a nonspecific marker of tissue damage, for supporting diagnoses like hemolysis and some cancers, and for staging or monitoring certain malignancies (e.g., lymphoma, germ cell tumors).

Clinical Use Cases

  • Supporting diagnosis and monitoring of hemolytic anemia and thrombotic microangiopathies.
  • Assessing tissue injury in conditions such as myocardial infarction (historically), liver disease, and muscle damage (alongside more specific markers).
  • Staging and prognostication in hematologic malignancies and germ cell tumors.
  • Evaluating and monitoring lung injury, pneumonia, or COVID‑19–related tissue damage in some settings.

Specimen Types

  • Serum.
  • Plasma (heparin or EDTA, depending on laboratory protocol).

Measurement Methods

  • Kinetic spectrophotometric enzyme assay (measuring rate of NADH oxidation or formation).
  • Automated clinical chemistry analyzers using standardized LDH methods (e.g., IFCC‑recommended).

Test Preparation and Influencing Factors

  • No fasting or special preparation typically required.
  • Hemolysis during sample collection or handling falsely elevates LDH due to red blood cell enzyme release.
  • Strenuous exercise, intramuscular injections, or recent surgery may increase LDH.
  • Certain drugs or alcohol use, as well as liver or muscle diseases, can alter levels and must be considered in interpretation.

Synonyms

  • Lactate dehydrogenase.
  • LD.
  • LDH (lactic dehydrogenase).

Further Reading

  • “Lactate Dehydrogenase” – MedlinePlus, U.S. National Library of Medicine;