Clinical and Diagnostic Significance of Lactate Dehydrogenase and Its Isoenzymes in Animals

Lactate dehydrogenase (LDH) is widely distributed enzyme in cells of various living systems where it is involved in carbohydrate metabolism catalyzing interconversion of lactate and pyruvate with NAD+/NADH coenzyme system. Cells of tissues are direct source of lactate dehydrogenase isoenzymes that are naturally distributed in blood plasma/serum of animals and humans producing characteristic profile. This profile depends on intracellular isoenzyme concentration in all tissues that contribute to the common pool of lactate dehydrogenases in plasma/serum as a consequence of natural cell degradation. LDH is widely distributed in the body, high activities are found in the heart, liver, skeletal muscle, kidney, and erytrocytes, whereas lesser amounts are found in the lung, smooth muscle, and brain. Because of its widespread activities in numerous body tissues, LDH is elevated in a variety of disorders. There are many conditions that contribute to increased activity of LDH. An elevated total LDH value is a rather nonspecific finding. Therefore, LDH assays assume a more clinical significance when separated into isoenzyme fractions. The activity of LDH and its serum and tissue patterns and composition show great variations between the species. These differences do not allow using catalytic activities of LDH isoenzymes from one species to another. Instead, the pattern of serum LDH isoenzymes should be interpreted in respect to its species origin that is important in particular in veterinary medicine. Determination of total LDH activity and its isoenzyme pattern in serum of mammals had become one of the biochemical indicators in the assessment of organ disorders. When the content of cells is released from tissue to plasma, as on cell injury, the LDH isoenzyme pattern of the serum changes in favour of the profile of the affected organ (tissue) that can be used in the diagnostic practice.

Utility of serum lactate dehydrogenase in the diagnosis of megaloblastic anemia

Background: Megaloblastc anemia corresponds to severe macrocytic anemia with hypersegmented neutrophils and very high serum Lactate Dehydrogenase (LDH). The present study was undertaken to evaluate the utility of serum LDH and chloroform inhibited serum LDH in the diagnosis of megaloblastic anemia and to observe if this can be used to differentiate megaloblastic anemia from iron deficiency anemia and hemolytic anemia.Methods: The present study was carried out on 75 patients of anemia categorised on bone marrow examination (into megaloblastic and non-megaloblastic anaemia) to evaluate the efficacy of total serum LDH levels and LDH isoenzyme pattern in the diagnosis of megaloblastic anemia. About 25 healthy adults were taken as controls.Results: In megaloblastic anemia, total serum LDH level was found to be increased to about nineteen folds and in hemolytic anemia it was found to increased four folds as compared to normal. On statistical analysis this increased total serum LDH level in megaloblastic anemia and hemolytic anemia as compared to control group was found to be significant.In the present study serum LDH level above 3000IU/L was associated with megaloblastic anemia and serum LDH level below 900IU/L was suggestive of iron deficiency anemia. The chloroform inhibition test was less than 25% in megaloblastic anemia and more than 25% in hemolytic anemia and these differences were found to be statistically significant (t=9.62, df=49, p<0.001).Conclusions: Total serum LDH levels more than 3000IU/L are diagnostic of megaloblastic anemia. Reversed LDH isoenzyme pattern (LDH1>LDH2) by chloroform inhibition test is an adjuvant in the diagnosis where total serum LDH levels are between 451-3000IU/L and can also differentiate megaloblastic anemia from hemolytic anemia.

Variability of enzymatic systems in natural populations of Anthyllis vulneraria s. 1. from three geographic regions of Poland. Part I. Ontogenetic variability of enzymatic systems in three woundwort populations during plant development

Analysis of variation in the four enzymatic systems of three populations of <i>Anthyllis vulneraria</i> was made. Different polymorphism of enzyme .protein® in six terms of plant development was found by isoenzyme electrophoresis on polyacrylamide gel. Each population had a specific isoenzyme pattern and specific variability in the terms.