APPLICATION: Superseded by Troponin I in the diagnosis of myocardial infarction when testing is required >48 hours after the onset of chest pain. It is occasionally useful in the assessment of patients with liver disease or malignancy (especially lymphoma, seminoma, hepatic matastases); anaemia when haemolysis or ineffective erythropoiesis suspected. Although it may be elevated in patients with skeletal muscle damage, it is not a useful or diagnostic test in this situation.
INTERPRETATION: The ubiquitous tissue distribution of LD makes it a non-specific indicator of disease. Increased levels are found in myocardial infarction, liver disease, haemolysis, ineffective erythropoiesis, some malignancies (especially non-Hodgkins lympyoma) and numerous other disease processes involving tissue damage. Haemolysis during collection, delays in processing, or refrigeration of unseparated blood may cause an artefactual increase in enzyme activity.