LACTIC ACID DEHYDROGENASE
Lactic acid dehydrogenase is found chiefly in the heart, skeletal muscles, kidneys, and liver, as well as all cells.
In pathological states, elevated levels indicate damage to the above areas and is used to determine myocardial and pulmonary infarction.
In physiological states, LDH catalyzes the conversion of pyruvate ( the final step in glycolysis) to lactate and back, as it converts NADH to NAD+ and back.
A dehydrogenase is an enzyme that transfers a hydride from one molecule to another.
When sugar and water (fatty acid metabolism) are exchanged across a muscle cell interface, a by-product called lactic acid is produced.
When lactic acid combines with the carbon dioxide of the venous blood you have a hydrogen displacement. Lactic acid now becomes lactic acid dehydrogenase.
Lactic acid dehydrogenase, therefore, is a glycolytic enzyme that functions as a catalyst in carbohydrate metabolism to produce energy.
The pancreas via insulin and the posterior pituitary via ADH are responsible for this sugar and water exchange across the muscle cell interface. Lactic acid dehydrogenase indicates the active exchange of sugar across the membrane (muscle cell interface) utilizing chloride, zinc, and selenium.
The utilization of these minerals creates glycolysis.
LDH then from a physiological perspective determines pancreatic function regulating the amount of glucose into muscle.
It is also important to note that sugar metabolism is very complex and does involve a series of other organs.
Ranges for LDH are between 0-220; again it is rather obvious that LDH is a by-product of sugar metabolism and a 0 figure could not be construed as a low normal range. I feel that the range should start at 80.
You will find many patients with a low LDH having problems with decreased function causing heart, skeletal muscle (weakness, loss of strength, muscle wasting), kidney and liver dysfunction, and eventual wasting away of these organs.
