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Lactate dehydrogenase in the blood.
Last reviewed: 05.07.2025
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Reference values (norm) for total lactate dehydrogenase activity in blood serum are 208-378 IU/l.
Lactate dehydrogenase is a glycolytic zinc-containing enzyme that reversibly catalyzes the oxidation of L-lactate to pyruvic acid and is widespread in the human body. The highest lactate dehydrogenase activity is found in the kidneys, cardiac muscle, skeletal muscles, and liver. Lactate dehydrogenase is found not only in serum, but also in significant quantities in erythrocytes, so the serum for testing should be free of hemolysis. Most human organs and tissues contain five lactate dehydrogenase isoenzymes. The nature of the LDH isoenzyme spectrum and the type of metabolism in the tissue correlate with each other. In tissues with predominantly aerobic metabolism (heart, brain, kidneys), LDH 1 and LDH 2 isoenzymes predominate. In tissues with pronounced anaerobic metabolism (liver, skeletal muscles), the LDH4 and LDH5 isoenzymes predominate . All five LDH isoenzymes are constantly detected in the blood serum of a healthy person. A pattern can be observed in relation to the activity of lactate dehydrogenase isoenzymes: the activity of LDH2 > LDH1 > LDH3 > LDH4 > LDH5 . Damage to one or another organ changes the isoenzyme spectrum of the blood serum, and these changes are due to the specificity of the isoenzyme composition of the damaged organ.
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