How much analysis is done on ldg. Lactate dehydrogenase (LDH, LDH) in the blood: what is it, the norm in the analysis, the reasons for the increase. When this analysis is prescribed

LDH (L-lactate-NAD-oxidoreductase, EC 1.1.1.27) is a zinc-containing enzyme that reversibly catalyzes the oxidation of lactate to pyruvate. LDH is a tetramer, contains subunits M and H. In the cytoplasm of cells and blood serum, LDH is represented by 5 isoenzymes, designated according to their mobility to the anode in an electric field: LDH-1 (NNNN), LDH-2 (NNNM), LDH-3 (HHMM), LDG-4 (HMMM) and LDG-5 (MMMM). LDH is present in almost all organs and tissues of the body, while the distribution of LDH isoenzymes is organ-specific. LDH-4 and LDH-5 predominate in the liver and skeletal muscles, tissues with a predominantly anaerobic metabolism, LDH-1 and LDH-2 - erythrocytes, leukocytes, myocardium, kidneys - tissues with aerobic metabolism, the highest LDH-3 content - in lungs, lymphoid tissue, platelets and tumors.

MI is usually accompanied by a 3-4-fold increase in total LDH activity; a similar increase in LDH is observed with myocarditis, heart rhythm disturbances. With MI, an increase in the total activity of LDH in the blood serum is noted after 8-10 hours, and reaches its maximum activity after 48-72 hours. The release of myocardial isoenzymes of LDH during MI into the blood leads to an increase in the activity of LDH-1 and LDH-2. The activity of LDH-1 increases 12-24 hours after the onset of acute MI, coinciding in time with the maximum activity of CK-MB and ahead of the onset of the peak of total LDH activity (24 hours).

The identification of the spectrum of isoenzymes characteristic of MI is possible with stagnation of blood in the liver and kidneys due to heart failure, with ischemic damage to some organs due to a sharp decrease in cardiac output. Currently, the determination of the activity of LDH and its isoenzymes is not included in the list of mandatory tests for the diagnosis of MI due to lack of specificity.

Myopathies, liver diseases, megaloblastic and hemolytic anemias, acute and chronic kidney diseases lead to an increase in LDH activity. An increase in LDH activity is noted with liver damage, but this increase is not as great as an increase in ALT and AST activity. A special increase (10 times higher than the upper limit of the norm) is noted in toxic hepatitis, accompanied by jaundice.

A physiological increase in the level of LDH in the blood occurs during pregnancy, in newborns, and also after intense physical activity.

Indications for research:

Liver disease;
identification of myocardial lesions;
myopathy;
hemolytic anemia;

Serum or plasma (EDTA, heparin) without signs of hemolysis. Storage of samples for no more than 2 days at 18-25 ° C. Storing samples at 4–8 ° C or freezing will reduce enzyme activity.

Research methods. Method based on IFCC guidelines. LDH catalyzes the oxidation of lactate to pyruvate at alkaline pH, while NAD + is reduced to NADH. The rate of increase in the optical density of the reaction mixture at 340 nm, reflecting the increase in the concentration of NADH, is proportional to the activity of the enzyme in the sample.

Increased values:

Myocardial damage;
liver damage;
skeletal muscle damage, inflammatory and degenerative diseases;
pulmonary embolism and infarction;
kidney disease;
diseases and conditions accompanied by cell breakdown;
malignant tumors of any localization;
taking anabolic steroids, ethanol, hepatotoxic drugs.

Reduced values:

Isozymes LDH-1 and LDH-2

LDH-1 and LDH-2 are isozymes with a high content of H-subunits; they can use α-ketobutyrate as a substrate and catalyze its transformation into α-hydroxobutyrate; isoenzyme LDH-1, which has a high affinity for the named substrate, is called α-hydroxybutyrate dehydrogenase (α-HBDH). A parallel study of the activity of total LDH and α-HBDH can be used for differential diagnosis of liver and heart diseases: in case of damage to the heart muscle, an increase in the activity of the enzyme is due to an increase in LDH-1 (α-HBDH), in case of damage to the liver parenchyma - by the isoform of LDH-5, LDH activity -1 is not incremented.

Indications for research:

Identification of myocardial lesions;
hemolytic anemia;
malignant neoplasms;
pulmonary embolism (differential diagnosis with myocardial infarction).

Features of taking and storing samples. Serum or plasma (EDTA, heparin) without signs of hemolysis. Storage of samples for no more than 2 days at 18-25 ° C. Storing samples at 4–8 ° C or freezing will reduce enzyme activity.

Research methods. LDH catalyzes the conversion of α-ketobutyrate to α-hydroxybutyrate, while oxidation of β-NADH2 to β-NAD occurs. The rate of decrease in optical density at a wavelength of 340 nm is proportional to the activity of the enzyme in the sample.

Increased values:

Myocardial damage;
diseases and conditions accompanied by the breakdown of blood cells;
acute kidney disease.

Reduced values:

Genetic disorders or complete absence of LDH subunits.

LDH blood test is lactate dehydrogenase (LDH)- an enzyme contained in the cells of the heart muscle, liver, kidneys, lungs, skeletal muscles. In this regard, in clinical practice, separate isoenzymes are isolated: LDH1 and LDH2 (contained mainly in the myocardium, kidneys), LDH3 (found mainly in the lung tissue), LDH4 and LDH5 (found in the greatest quantities in the liver and skeletal muscles), the information content of which higher than when determining the total LDH.

Enhancement LDH (especially LDH1 and LDH2) is most often observed in acute myocardial infarction, while in angina pectoris (including unstable) this indicator remains normal, which makes it possible to use it along with creatine kinase (for details, see the position "creatine kinase" and "creatine kinase MB ») For the differential diagnosis of these conditions in case of a questionable ECG picture. A moderate increase in LDH is also observed in patients with acute myocarditis, severe heart failure with congestion in the liver, as well as in the development of pulmonary embolism. A significant increase in both total LDH and its isoenzymes LDH4 and LDH5 is observed in acute hepatitis, liver cirrhosis in the acute stage, as well as in liver cancer. LDH activity also increases with obstructive jaundice (most often - when the bile ducts are blocked by a stone or are compressed by a tumor) and hemolytic anemias. A moderate increase in this indicator is possible with extensive traumatic muscle injuries and with progressive muscular dystrophy.

Decrease LDH activity in clinical practice does not matter.

Biological material: blood serum

In diseases accompanied by tissue damage and cell destruction, the LDH activity in the blood increases. In this regard, it is an important marker of tissue destruction. Despite the fact that an increase in the activity of the enzyme does not indicate any specific disease, its determination in combination with other laboratory tests helps in the diagnosis of pulmonary infarction, muscular dystrophy and hemolytic anemia. Increased LDH activity can be detected in newborns, pregnant women and after intense physical exertion.

Previously, combined assays for LDH, aspartate aminotransferase and creatine kinase were widely used in the diagnosis of myocardial infarction. Now for this purpose, the level of troponin is determined as a more specific marker of damage to the heart muscle. But the study of LDH activity remains an auxiliary analysis in the differential diagnosis of pain in the chest.

Monitoring the course of myocardial infarction. An increase in LDH activity is observed 12 to 24 hours after a heart attack; the maximum activity is noted after 24 - 48 hours. The increased activity of the enzyme lasts up to 10 days. LDH activity depends on the size of the focus of myocardial lesion, and the dynamics of its decrease in the process of recovery depends on the intensity of recovery processes in the heart muscle.

Determination of LDH activity makes it possible to differentiate between true myocardial infarction and clinically similar attacks of angina pectoris: with a heart attack, the total LDH activity increases and, as a result, its value is several times higher than the normal level, at the same time, even with severe attacks of angina pectoris, the level of LDH activity is normal. The decrease in the enzyme activity in the postinfarction period occurs 2 times slower than the normalization of such markers of myocardial damage as creatine kinase and AST, which is especially valuable for late diagnosis of the lesion.

Indications for the purpose of the study

1. Diseases of the hepatobiliary system;
2. Myocardial infarction (early diagnosis, differential diagnosis and monitoring);
3. Tumors;
4. Anemias accompanied by hemolysis.

Preparation for research

GENERAL RULES FOR PREPARING FOR RESEARCH:

1. For most studies, it is recommended to donate blood in the morning, from 8 to 11 o'clock, on an empty stomach (at least 8 hours should pass between the last meal and blood sampling, you can drink water as usual), on the eve of the study, a light dinner with restriction eating fatty foods. For infection tests and emergency tests, it is permissible to donate blood 4-6 hours after the last meal.

2. ATTENTION! Special preparation rules for a number of tests: strictly on an empty stomach, after 12-14 hours of fasting, blood should be donated for gastrin-17, lipid profile (total cholesterol, HDL cholesterol, LDL cholesterol, VLDL cholesterol, triglycerides, lipoprotein (a), apolipoprotein A1, apolipoprotein B); The glucose tolerance test is performed in the morning on an empty stomach after 12-16 hours of fasting.

3. On the eve of the study (within 24 hours), exclude alcohol, intense physical activity, taking medications (in agreement with the doctor).

4. For 1-2 hours before donating blood, refrain from smoking, do not drink juice, tea, coffee, you can drink non-carbonated water. Eliminate physical stress (running, fast climbing stairs), emotional excitement. It is recommended to rest and calm down 15 minutes before donating blood.

5. You should not donate blood for laboratory research immediately after physiotherapy procedures, instrumental examination, X-ray and ultrasound examinations, massage and other medical procedures.

6. When monitoring laboratory parameters in dynamics, it is recommended to conduct repeated studies under the same conditions - in the same laboratory, donate blood at the same time of day, etc.

7. Blood for research must be donated before taking medications or not earlier than 10-14 days after drug withdrawal. To assess the control of the effectiveness of treatment with any drugs, a study should be carried out 7-14 days after the last dose of the drug.

If you are taking medications, be sure to notify your doctor about it.

The glycolytic intracellular (cytoplasmic) enzyme lactate dehydrogenase (LDH, LDH), which accelerates the conversion of lactic acid into pyruvic acid, and also catalyzes the reverse reaction (reversible oxidation of L-lactate into pyruvate), is present, without exception, in all tissues of the human body. The highest LDH content is found in the heart, hepatic and renal parenchyma, skeletal muscles, red blood cells, where the enzyme is presented in the form of five isoenzymes (isoenzymes): LDH-1, LDH-2, LDH-3, LDH-4, LDH-5. The electrical mobility of these isoenzymes fully corresponds to that of globulins - α 1, β 1, γ 1, γ 2. The main concentration of LDH is concentrated inside the cells, serum is noticeably inferior in this regard.

An adult who does not complain about his health the total activity of lactate dehydrogenase in the blood serum normally ranges from 0.80 to 4.00 mmol/ (h l) or 38 - 62 U / l ( at 30 ° C).

Distribution of fractions in plasma. Age and norm

The first fraction (LDH-1 or HHHH tetramer) originates mainly in the heart muscle and increases significantly in blood serum with myocardial damage.

The second, third, fourth fractions (LDH-2, LDH-3, LDH-4) begin to actively enter the plasma in pathological conditions accompanied by massive death of platelets - platelets, which occurs, for example, in the case of such a life-threatening condition as pulmonary embolism (PE).

The fifth isoenzyme (LDH-5 or MMMM tetramer) originates from the cells of the hepatic parenchyma and is secreted into the blood plasma in large quantities at the acute stage of viral hepatitis.

Due to the fact that different types of tissues accumulate and secrete different concentrations of LDH, fractions of lactate dehydrogenase isoenzymes are distributed unevenly in blood plasma:

Isozyme	Serum concentration
LDG-1	17 - 27% (0.17 - 0.27 rel. Units)
LDG-2	27 – 37% (0,27 – 0,37)
LDG-3	18 – 25% (0,18 – 0,25)
LDG-4	3 – 8% (0,03 – 0,08)
LDG-5	0 – 5% (0,00 – 0,05)

The activity of lactate dehydrogenase in red blood cells (erythrocytes) is 100 times higher than the levels of the enzyme contained in the blood plasma, and increased values are noted not only in pathological conditions, a number of physiological conditions, for example, pregnancy, the first months of life, or excessive physical effort on our part also contribute to an increase in LDH activity. Significant differences in normal levels of this indicator are also due to age and gender, as evidenced by the table below:

Meanwhile, the indicators of the norm for blood LDH are always approximate, they should not be memorized once and for all, for the reason that the analysis can be performed at a temperature of 30 ° C or 37 ° C, the level is calculated in various units (μkat / l, mmol / ( h l), U / l or U / l). But if there is an urgent need to independently compare your own results with the standard options, it will be useful to start by asking the institution that performed the analysis, the methods of its conduct and the units of measurement used by this laboratory.

The excretion of lactate dehydrogenase isoenzymes (LDH-4, LDH-5) by the kidneys does not go over the level of 35 mg / day (the rate of excretion).

Reasons for increasing LDH

The level of LDH activity is increased in almost any pathological process, which is accompanied by inflammation and death of cellular structures, therefore, the reasons for the increase in this indicator are primarily considered:

Acute phase (a more detailed description of changes in the LDH spectrum in necrotic myocardial damage will be presented below);
Functional insufficiency of the cardiac and vascular system, as well as respiratory organs (lungs). Involvement of lung tissue in the process and the development of circulatory failure in the pulmonary circulation (the level of LDH is increased due to the activity of LDH-3 and, to some extent, due to LDH-4 and LDH-5). Weakening of cardiac activity leads to circulatory disorders, symptoms and an increase in the activity of the LDH-4 and LDH-5 fractions;
Damage to red blood cells (pernicious and), causing tissue hypoxia;
Inflammatory processes affecting the lungs, as well as the renal or hepatic parenchyma;
Acute period of viral hepatitis (in the chronic stage, LDH activity, as a rule, does not leave the normal range);
Malignant tumors (especially with metastasis), localized mainly in the liver tissue. Meanwhile, a strict correlation, in contrast to myocardial infarction (the larger the focus, the higher the LDH activity) between the progression of the oncological process and the change in the spectrum of lactate dehydrogenase is not traced;
Various hematological pathology (, acute, granulocytosis, chronic myeloid leukemia, or folic acid deficiency);
Massive destruction of platelets, the cause of which is often not provided with sufficient selection for individual blood systems (for example, HLA);
Diseases of the musculoskeletal system, in the first place - damage to skeletal muscles (trauma, atrophic lesions, mainly at the initial stage of the development of the disease).

LDH and cardiac muscle necrosis

The study of the glycolytic enzyme has a very important diagnostic value in the defeat of the heart muscle, therefore refers to the main enzymatic tests that determine myocardial infarction on the first day development of a dangerous necrotic process localized in the heart muscle (8 - 12 hours from the onset of pain syndrome). The increase in enzyme activity occurs primarily due to the LDH-1 fraction and partly due to the second fraction (LDH-2).

After a day or two from a painful attack, the blood LDH level reaches its maximum values and in most cases retains a high degree of activity for up to 10 days. It should be noted that activity is in direct proportion to the area of myocardial damage(the larger the size of the focus, the higher the value of the indicator). Thus, myocardial infarction, initially diagnosed with the help of such laboratory tests as the determination of creatine kinase and the CF fraction of creatine kinase, in a day can already be confirmed by this enzymatic study (LDH is increased and increased significantly - 3 - 4 ... up to 10 times).

In addition to an increase in the total activity of lactate dehydrogenase and an increase in the activity of the LDH-1 fraction, the LDH / LDH-1 ratio or HBDH (hydroxybutyrate dehydrogenase) and the LDH-1 / LDH-2 ratio are of particular value for detecting acute myocardial infarction. Considering that the values of HBDH in the acute period of the disease change significantly upward, and the total activity of lactate dehydrogenase will be reduced relative to rather high values of LDH-1, then the LDH / HBDH ratio will noticeably fall and will be below 1.30. At the same time, the LDH-1 / LDH-2 ratio, on the contrary, will show an upward trend, striving to reach 1.00 (and sometimes even cross this line).

Other reasons for changing odds

The above parameters, in addition to necrotic damage to the heart muscle, are subject to change in the case of other serious diseases:

Hemolytic anemia of various origins (LDH / HBDH decreases and becomes below 1.3);
Megaloblastic anemia (the content of the first fraction significantly exceeds the concentration of the second);
Conditions accompanied by increased cell destruction (acute necrotic process);
Neoplasms localized in the glands of the female and male genital spheres: ovarian dysgerminoma, testicular seminoma, teratoma (only an increase in the concentration of LDH-1 is noted here);
Lesions of the renal parenchyma.

Thus, the main culprits, and, therefore, the main reasons for changes in the concentration of the described parameters in the blood serum can be considered conditions associated with the destruction of cells of the hepatic and renal parenchyma, as well as blood cells (platelets, erythrocytes).

Selected nuances

For the study of LDH in the blood, 1 ml of serum is sufficient, which is obtained from blood donated, as for any other biochemical test, in the morning on an empty stomach (although, if there is a question about the diagnosis of acute MI, then these rules, of course, are neglected).

In a laboratory study of LDH, hemolysis leads to a distortion of the analysis results (overestimates them). And when exposed to heparin and oxalate, the activity of the enzyme, on the contrary, in the serum will be reduced in comparison with the real values of LDH in the blood. To prevent this from happening, you should start working with the material as early as possible, first of all separating the clot with shaped elements from the serum.

Video: specialist about LDH

An LDH (lactate dehydrogenase) test is an analysis of the level in the blood of an enzyme that oxidizes glucose and is responsible for the synthesis of lactic acid.

This indicator is non-specific and does not correspond to certain diseases and pathologies, since this enzyme is contained in almost all tissues and cells of the body.The LDH test is an important indicator of the destruction of cells and tissues in the body. It is included in the list of required indicators.

Lactate dehydrogenase is a special substance found in most cells in the body. The greatest activity of this enzyme is observed in muscle tissue, and.

LDH analysis is a non-specific indicator of tissue destruction in the body. When the LDH index is assessed only in conjunction with other blood parameters.

The enzyme is present in the body in the form of five isoforms that differ not only in composition, but also in the place of concentration in the body. For example, LDH in isoform 1 is concentrated in the heart muscle. When the cells of the heart tissue are destroyed, LDH-1 is released into the blood, and its concentration increases. This indicator is used for early diagnosis of myocardial infarction.

LDH in isoform 5 is concentrated in liver tissue and muscles, and LDH in isoform 3 in lung tissue. Together with other, more specific blood parameters, LDH is used as a marker of various pathological processes in the body.

Depending on which LDH isoform prevails in the tissue, the type of cleavage depends: aerobic or anaerobic.

LDH analysis is mandatory when taking a biochemical blood test. It is prescribed for almost any and for prophylactic purposes.

More information about the LDH enzyme can be found in the video:

Particular attention is paid to the indicator of lactate dehydrogenase in the following cases:

If you suspect. With anemia, they are destroyed faster and the level of LDH contained in blood cells increases. An LDH test is prescribed for symptoms of anemia, for example, pallor of the skin, chronic fatigue, dizziness, tinnitus.
To control, diagnose and test the effectiveness of the treatment of myocardial infarction. With the destruction of the heart muscle, the level of LDH increases significantly.
If you suspect a tumor disease. With cancer, many cells in the body begin to break down, releasing an enzyme into the bloodstream.

Preparation and procedure

To find out the LDH level, you need to donate blood from a vein to. The procedure itself is standard: the patient comes with a coupon to the laboratory at the appointed time and donates blood from a vein. In paid laboratories, you can donate blood without a coupon and a record.

Since LDH is a non-specific indicator, special preparation for the procedure is not required. Used in the test. In order for it to be suitable for analysis, it is desirable to carry out standard simple preparation.

The reliability of the test results depends not only on laboratory technicians and compliance with the rules of blood sampling, but also on the patient himself.

Blood from a vein is donated in the morning, preferably before 10 am. You do not need to follow any special diet, but in the morning before the analysis you cannot eat anything, otherwise the blood will clot and become unsuitable for analysis. The last meal should be 6-8 hours before the visit to the laboratory.
Despite the absence of a diet, it is undesirable to overeat and consume large amounts of fatty and protein foods the day before the test. The increased content of fat and protein in the blood leads to a turbidity of the blood serum, as a result, it coagulates, and it becomes impossible to conduct a test.
It is not recommended to take alcohol on the eve of donating blood. It will negatively affect the state of the body, which will invariably affect the blood counts. Results may be unreliable.
Smoking also has a negative effect on the condition of the blood. It is undesirable to smoke on the day of the examination or at least an hour before donating blood.
It is not recommended to take any medications on the day of blood donation. All medications you take should be reported to your doctor. Aspirin, oral contraceptives and strong antidepressants can affect blood clotting, distort the indicators.
Exercise can also affect the test result. The day before visiting the laboratory and on the day of donating blood, it is undesirable to engage in intensive sports.

Explanation: the rate and reasons for the decrease in the indicator

Only a doctor should decipher the results. It is impossible to talk about any diseases on the basis of only the LDH indicator. For a complete picture, you need to evaluate all blood parameters.

The LDH rate may vary depending on the age or condition of the patient. For example, for athletes and pregnant women, the normal level of LDH is slightly higher than for the rest.

LDH blood norm:

In the blood of newborn babies, the level of LGD is always elevated. The norm is considered to be an indicator from 220 to 600 units / l.
In children, after a year, this indicator decreases to 115-300 units / l.
For women and men, the norm is practically the same. The lower limit for all is the same 125 units / l, and the upper limit for women is 210 units / l, for men - 225 units / l.

A low LDH level (below 125 U / L in an adult) is very rare and is almost never considered as an indicator of the pathological state of the body.

A reduced enzyme value indicates that glucose is being broken down very actively in the body.

Among the reasons for the decrease in the level of lactate dehydrogenase in the blood, the following can be distinguished:

A large amount of vitamin C. If a person actively uses ascorbic acid or products containing it, the level of LDH in the blood decreases.
Taking medications that reduce the amount of an enzyme in the blood. These drugs include Amikacin, Naltrexone, Enalapril, Metronidazole, Cefotaxime.
The presence of oxalates and urea in the blood, neutralizing LDH. Usually, similar phenomena are observed with stones in the kidneys, bladder, urinary ducts.

Reasons for the increase in the indicator

The reasons for the increase in blood can be both physiological (, physical activity, newborn age) and pathological.

It is impossible to determine the disease only by the level of LDH, since this is a non-specific indicator, it only indicates the presence of destructive processes in the tissues of the body.

Reasons for increasing LDH:

Myocardial infarction. With myocardial infarction, muscle tissue suffers. It breaks down, releasing various enzymes into the blood, one of which is LDH. helps to identify myocardial infarction even before the onset of symptoms. LDH in the blood rises within a day after the onset of the disease, - after 4 hours, - after 4-8 hours.
... Anemia is accompanied by reduced levels, which, when broken down, release LDH. With anemia, as a rule, there is a lowered level of iron in the blood and an increase in the level of LDH. most common. It is often caused by poor diet and is regulated with help.
Leukemia. With leukemia (an oncological disease of the blood, accompanied by an abnormal, abnormal production of blood cells), the activity of many enzymes increases:, LDH, the level of and increases. Conversely, the glucose and fibrinogen content decreases.
Malignant tumors. Most often, oncology is diagnosed with the help. With the help of biochemistry, one can only suspect a malignant tumor. Cancer is often accompanied by an increased level of AST, LDH. Tumor processes affect many tissues and organs, so many blood parameters can change.
Acute pancreatitis. An attack of acute pancreatitis is accompanied by severe pain and often requires hospitalization of the patient. In pancreatitis, first of all pay attention to the level of (pancreatic enzyme). The level of bilirubin, LDH may also increase.

Normalization of LDH levels in the blood

To normalize the level of LDH in the blood, you need to correctly determine the reason for its increase, taking into account other and blood parameters. Only the elimination of the disease causing an increase in LDH in the blood will give a result.

Features of the treatment of pathology:

Treatment of myocardial infarction begins at the first symptoms of the disease or immediately after, revealing a heart attack. The load on the heart is reduced to the patient, fresh air is provided, medications are administered to normalize blood circulation, and maintain heart function. During treatment, the patient constantly donates blood so that the doctor can monitor the effectiveness of treatment. With sufficiently effective treatment, the level of LDH and other indicators will decrease.
If an increase in the level of LDH caused iron deficiency anemia, iron supplements containing foods rich in iron, ascorbic acid are prescribed, and walks in the fresh air are recommended. During treatment, blood is donated to monitor the effectiveness. If the treatment is effective and the cause of the anemia is eliminated, the LDH level will fall, and - rise.
Treatment of malignant tumors is carried out in a complex manner using various aggressive methods of influencing cancer cells, for example, chemotherapy, radiation therapy. Not so long ago, a drug was invented that blocks the production of LDH in the cells themselves, which makes it possible to reduce tumor growth and even get rid of it completely. Such treatment is effective in the initial stages. In the absence of metastases, an operation is prescribed to remove the tumor (to replace the bone marrow with leukemia).
Treatment of acute pancreatitis is most often carried out in a hospital setting, the level of LDH in the blood is constantly observed. The patient is prescribed pain relievers, digestive enzymes, plasma droppers, etc. If drug therapy has not yielded results, the patient is prescribed a lavage and, in extremely rare cases, an operation to remove it.

The LDH (lactate dehydrogenase) test is a non-specific test that is used when a number of diseases and conditions are suspected. The enzyme enters the blood plasma during the destruction of almost any cell in the body, including the bacterial one. Therefore, the level of LDH in the blood is a general indicator of tissue and cellular damage. Sometimes the assessment of the concentration of a substance is carried out on the cerebrospinal or pulmonary fluid in the presence of certain diseases.

The value of the enzyme in the body

Interest in what LDH is in a biochemical blood test is primarily associated with myocardial infarction. Previously, this test was used to diagnose and monitor damage to heart tissue, but now the troponin test is considered more accurate and informative. Lactate dehydrogenase (LDH) is not a specific indicator of cardiac cell damage and is no longer used in patients with suspected acute coronary syndrome. Usually, the decoding of the biochemical blood test contains this indicator. Lactate dehydrogenase in the blood is an important enzyme involved in the reactions:

Oxidation of glucose;

Lactic acid production.

A feature of the enzyme is that it does not accumulate in cells, but is completely broken down and excreted. LDH is needed to convert glucose into energy for all cells in the body to function. The reaction is mediated by oxygen, which helps to break down glucose into water, carbon dioxide and energy. Without oxygen, energy production is reduced by a factor of 20 and lactic acid accumulates. The enzyme LDH is required for its oxidation and return to glucose metabolism. Unlike healthy cells, cancers feed without oxygen.

When is the analysis prescribed?

The test is used when acute and chronic tissue damage is suspected, as well as to assess progressive diseases. In rare cases, the analysis can help identify the target organ damage.

The enzyme is determined in a venous blood sample. After injury, LDH is increased, rises for 48 hours and reaches a maximum after 2-3 days, then gradually decreases. The normal indicator is restored in 10 days.

Research shows that LDH blood chemistry is an indicator of the development and progress of cancer. Even after taking into account the factor of age, stage of disease in patients, a strong association with the risk of death persisted. This relationship was valid for all types of malignant tumors.

The LDH blood test can be used to identify and evaluate:

Acute or chronic tissue damage;

Progression of anemia and severe infection;

The course of cancer after chemotherapy, leukemia, melanoma, neuroblastoma. High values indicate poor prognosis of patient survival.

The doctor prescribes the determination of the level of LDH in other body fluids:

To distinguish bacterial and viral meningitis by analyzing cerebrospinal fluid.

To identify the cause of the accumulation of exudate in the chest or abdomen (pleural, peritoneal and pericardial fluids) due to trauma and inflammation, or due to an imbalance in the pressure within the blood vessels and the amount of protein in the blood.

A blood test for LDH (biochemistry) is taken on an empty stomach from a vein.

The last meal 8 hours before the examination should not contain too fatty and protein foods.

Be sure to inform if you need to take medications regularly. Aspirin, hormonal contraceptives, and antidepressants affect clotting and may be overestimated.

Intense training the day before can lead to an overestimation of the enzyme, as it increases energy expenditure and the need to break down glucose.

Many factors influence the results of the analysis, and they are not always a cause for concern and further examination:

Blood samples lead to false positive results. Violation of the rules for storing samples, rough processing affects the accuracy.

With an increased number of platelets, serum LDH also increases and does not show a real picture.

When hospitalized with suspected myocardial infarction and acute pancreatitis, LDH analysis is performed without taking into account the recommendations. Often, the LDH index is used to assess the dynamics of the disease and the patient's recovery.

The norm of LDH in the body and interpretation of the analysis

When analyzing blood, the norm is usually indicated in units / l, which means a unit per liter. The interpretation of the analysis takes into account the age and gender of the patient. A relatively small amount of the enzyme is found in the blood of a healthy adult. In a child under two years of age, the rate is considered to be within 430 units / l.

An increase in lactate dehydrogenase occurs during pregnancy, in newborns, in professional athletes.

By the identified marker, it is impossible to determine which cells were damaged. Therefore, it is necessary to know, when decoding LDH, what is it isozymes. Some laboratories conduct additional tests that determine several forms of a substance, starting with the most mobile:

The first indicates a problem with the heart, kidneys, and red blood cells;

The second is found mainly in cardiomyocytes and erythrocytes;

The third is found in the tissues of the lungs, endocrine glands and adrenal glands;

the fourth is an enzyme found in white blood cells, liver, placenta and male testes and muscle tissue;

The fifth is found in all organs containing LDH-4, as well as skeletal muscles.

Deciphering biochemistry for an increase in LDH in the blood is now considered less informative.

High values of all isoenzymes determine the pathology of several organs. Myocardial infarction with congestive heart failure causes lung damage and liver congestion. In cancer and autoimmune diseases such as lupus, lactate dehydrogenase is generally increased. Hypoxia, shock, and burns are accompanied by cell death, which indicates an increase in LDH. Caffeine also affects the amount of the enzyme in the blood.

The dynamics of the first isoenzyme is more sensitive and specific than the increase in LDH in general. Usually the level of the second isoenzyme is higher than the first. If the concentration of LDH-1 rises relative to LDH-2, a heart attack is diagnosed. Usually, the LDH norm in the blood is exceeded 12-24 hours after damage to the heart tissue and within two days in 80% of cases. A normal LDH-1 / LDH-2 ratio is reliable evidence that there has been no seizure. The ratio of total LDH to LDH-1 is called hydroxybutyrate dehydrogenase. Therefore, with a heart attack:

The LDH / HBDH figure is lowered (less than 1.30);

The LDH-1 / LDH-2 ratio approaches 1 and sometimes exceeds this value.

On the first day, myocardial infarction is diagnosed by the creatine kinase index, and a day later - by the enzymatic study of LDH. The activity of the substance is directly related to the area of damage to the heart muscle.

Other serious diseases are reflected in the ratio of isoenzymes and coefficients:

Hemolytic anemia is characterized by a low LDH / HBDH value - up to 1.3 and below;

With megaloblastic anemia, LDH-1 significantly exceeds LDH-2;

the general level increases with acute necrotic processes and cell death, such as damage to the renal parenchyma;

tumors in the gonads (ovaries and testes) are accompanied by an isolated increase in LDH-1.

Most often, LDH is increased due to the destruction of the tissues of the hepatic and renal parenchyma, and the death of platelets and erythrocytes.

LDH in a blood test is considered in relation to other indicators:

With anemia, the destruction of red blood cells occurs, which releases a large amount of LDH into the blood. The disease is diagnosed against the background of low hemoglobin. Weakness, pallor, shortness of breath may be indications for examination.

Blood cancer is associated with the production of abnormal blood cells, which is reflected in the levels of many indicators: LDH, aspartate aminotransferase, bilirubin, urea. At the same time, there is a decrease in the level of glucose and the blood clotting factor fibrinogen. A biochemical blood test allows you to suspect a pathology and direct the patient to identify tumor markers.

Along with the LDH in the blood, which indicates the death of pancreatic cells, bilirubin and glucose will increase. The primary indicator is the level of the pancreatic enzyme amylase.

Reasons for the increase

Elevated LDH levels can be caused by various medical conditions:

stroke;
some types of anemia (pernicious and hemolytic)
kidney and liver diseases;
muscular dystrophy;
pancreatitis;
Infectious mononucleosis;
some forms of cancer.

The enzyme concentration increases after the administration of anesthetics and taking aspirin, as well as after intense physical exertion. Normal and low LDH levels are not pathological. The factor that reduces the indicator is the consumption of a large dose of ascorbic acid (vitamin C).

The reasons for the increased lactate dehydrogenase are varied: HIV infection, sepsis, acute kidney disease, intestinal and lung infarction, bone fractures, and a rash on the body.

LDH is lowered when transudate accumulates in body cavities, such as the abdomen, usually caused by congestive heart failure or cirrhosis.