Causes of increased lactate dehydrogenase in the blood

The increased activity of lactate dehydrogenase under physiological conditions is observed in pregnant women, newborns, in persons after intensive physical exertion.

Increase in lactate dehydrogenase activity in myocardial infarction is noted 8-10 hours after its onset. After 48-72 hours, a maximum of activity is achieved (the increase is usually 2-4 times), it remains increased for 10 days. These terms may vary depending on the size of the site of the damaged muscle of the heart. The increase in the activity of total lactate dehydrogenase in patients with myocardial infarction is due to a sharp increase in lactate dehydrogenase ₁ and partially lactate dehydrogenase ₂. In patients with angina pectoris, an increase in lactate dehydrogenase activity is not observed, which makes it possible to use the definition of lactate dehydrogenase within 2-3 days after an anginal attack as a highly reliable criterion for the absence of damage to the heart muscle.

Moderate increase in the activity of total lactate dehydrogenase is observed in the majority of patients with acute coronary insufficiency (without myocardial infarction), myocarditis, with chronic heart failure, with congestive phenomena in the liver. In patients with cardiac arrhythmias, lactate dehydrogenase activity is usually normal, but with the use of electroimpulse therapy, it sometimes increases.

The source of increased lactate dehydrogenase activity can be pulmonary tissue in embolism and pulmonary infarction. The combination of normal activity of AST, increased activity of lactate dehydrogenase and an increase in bilirubin concentration can serve as a diagnostic triad of pulmonary embolism and for differentiating it from myocardial infarction. In pneumonia, enzyme activity may sometimes not increase.

In myopathies (muscular dystrophy, traumatic muscle damage, inflammatory processes, disorders associated with endocrine and metabolic diseases), an increase in lactate dehydrogenase activity is observed; With neurogenic muscle diseases, lactate dehydrogenase activity does not increase.

In acute viral hepatitis, lactate dehydrogenase activity in the serum increases in the early days of icteric period; with mild and moderate forms of the disease quite quickly returns to normal levels. Heavy forms of viral hepatitis, and especially the development of hepatic insufficiency, are accompanied by a pronounced and prolonged increase in lactate dehydrogenase.

With mechanical jaundice, the activity of lactate dehydrogenase is normal in the first stages of the obstruction of the bile ducts, at a later stage, the activity of lactate dehydrogenase increases due to secondary damage to the liver.

In liver carcinomas or metastases of cancer, the lactate dehydrogenase activity may rise in the liver.

In the stage of remission with chronic hepatitis and cirrhosis of the liver, the activity of lactate dehydrogenase in the blood remains within normal limits or slightly increased. At an aggravation of the process, an increase in the activity of the enzyme is noted.

Increase in lactate dehydrogenase activity is characteristic for megaloblastic and hemolytic anemia, therefore its definition is used for differential diagnosis of Gilbert's disease (LDH in norm) and chronic hemolytic anemia (LDH is increased).

The activity of lactate dehydrogenase increases with acute and exacerbation of chronic kidney disease; in chronic renal diseases associated with uremia, it can be normal, but often increases after hemodialysis, which is due to the removal of enzyme inhibitors during this procedure.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]