An increase in the level of LDH in the blood causes. Lactate dehydrogenase (LDH) (venous blood)

Lactate dehydrogenase molecule

Lactate dehydrogenase (LDH) is a zinc-containing enzyme involved in a very common biochemical reaction in the body: the conversion of L-lactate to pyruvate and vice versa. The latter is necessary to start a cascade of reactions that result in the formation of ATP (energy molecules), carbon dioxide and metabolites necessary to build new biological molecules (amino acids, carbohydrates, fatty acids, gema).

LDH is present in all organs and tissues, but in most found in skeletal muscle cells, heart muscles, liver, kidneys, lymphatic vessels, blood cells: erythrocytes and platelets. Therefore, in order to obtain pure serum LDH values, it is worth making sure that the blood is taken correctly, whether there is hemolysis (massive destruction of blood cells) in it, due to which LDH of erythrocytes will also enter the serum.

The enzyme has its isoforms

Thanks to electrophoresis, different isoforms of LDH were isolated, which are indicated by the numbers 1-5, which is convenient for identifying the enzyme's belonging to certain tissues. For example, it was noted that the LDH-1 isoform is characteristic of tissues with a high aerobic metabolism - the heart muscle, kidneys, brain, while LDH-5 is more common in skeletal muscles and the liver. Moreover, skeletal muscles often work in anaerobic, airless conditions, as a result of which lactate is formed from pyruvate, which is metabolized in the liver, heart and other tissues.

Based on all of the above, two main functions of LDH can be distinguished:

1. biochemical function. Participation in a wide range of metabolic transformations at the cellular level, which provides the body with energy and molecules for building cells.
2. diagnostic function. Determining the concentrations of LDH, both different isoforms and the total amount, helps in the diagnosis of pathologies of various organs.

Enzyme levels in the blood

LDH in women is often slightly lower than in men, but the indicators should be within the normal range.

Causes of an increase in LDH in the blood

Heart failure is the cause of the increase in LDH-1 and LDH-2

1. Damage to the heart muscle: acute myocardial infarction, myocarditis, congestive heart failure. At the same time, an increase in LDH-1 and / or LDH-2 is noted.
2. Liver tissue damage, often massive: hepatitis, liver cirrhosis, primary tumor, or metastasis of a tumor of another organ to the liver. An increase in LDH-4.5 is noted.
3. Skeletal muscle injury or disease, inflammatory or degenerative, atrophic processes in them. LDH-4.5 mainly increases.
4. Blood diseases, especially those accompanied by massive cell breakdown: hemolytic anemia, B12 deficiency anemia, sickle cell anemia, acute leukemia, massive blood transfusion, pulmonary embolism, shock states. An increase in LDH-2,3,4 is noted.
5. Lung diseases: pneumonia, lung tumor, lung infarction.
6. Acute pancreatitis.
7. Kidney infarction.
8. Physiological reasons: childhood, pregnancy, severe and prolonged physical exercise, the first time after the transfusion of blood components.

Do not forget that it is not always possible to identify specific LDH isoforms, so even a general increase in the enzyme requires a thorough study of all organs that could be involved in the pathological process.

Causes of a decrease in LDH in the blood

Some drugs can lower LDH levels

Often low rates enzymes do not indicate a critical pathology in the body, but they can be detected in the following cases:

A consistently low LDH value in one person per various stages his life can talk about congenital mutations that led to the synthesis of an insufficiently active enzyme.

How to Suspect Abnormalities (Signs and Symptoms)

An increase in LDH levels is not accompanied by specific signs

An increase in LDH can be suspected when diseases and conditions are detected, as a result of which human tissues and organs experience pronounced stress: necrotic, inflammatory, tumor processes, cell breakdown due to exposure to external factor(trauma of any type, hemolysis). All this usually appears common symptoms: fever, asthenia, pain. The functions of damaged organs are also violated. For example, in myocardial infarction, the heart performs its pumping function inefficiently. The rest of the organs, like the heart itself, are poorly supplied with blood, which leads to a number of complications: organ ischemia, pulmonary edema, arrhythmia, and possibly death of the patient. Damage to the liver, for example, with the development of its cirrhosis, will lead to a violation of the synthetic and neutralizing functions of the organ: encephalopathy, swelling of the extremities and abdomen, jaundice, increased bleeding, etc. will appear.

It is extremely difficult to suspect a decrease in LDH. Usually a person does not notice pronounced changes in his body. However, children often have symptoms of asthenia: apathy, lethargy, drowsiness, weakness, lack of active movements.

Despite clinical suspicions about the concentration of LDH, biochemical analysis of venous blood serum will help to most accurately identify a deviation from the norm.

Indications for research

Hemolytic anemia - an indication for research

1. Early diagnosis of myocardial infarction, as well as differential diagnosis of myocardial infarction with angina pectoris, further monitoring of the patient's condition.
2. Diagnosis of anemia, accompanied by the breakdown of red blood cells (hemolysis).
3. Oncological processes of any localization.
4. Chronic diseases of the liver, pancreas.

Study preparation

Physical rest is an important condition for preparing for analysis

Research can be carried out both on a planned and emergency basis.

It is preferable to take blood for routine analysis in the morning on an empty stomach, after an overnight fast of 8-14 hours. Drinking clean water without gas is allowed. Dinner on the evening before the study should be light, but you should not completely starve for more than 14 hours. 2-3 days before the analysis, you should limit yourself to fatty, fried, sweet food, alcohol, coffee. Stress and especially heavy muscle load during preparation (also 2-3 days in advance) are prohibited! Smoking in the morning before the study is not recommended. Medicines that may affect the result can only be canceled by the attending physician, and not by the patient himself. In case of pregnancy, a woman should notify her doctor about this, as it is possible physiological enhancement LDH.

Emergency research is carried out at any time of the day. It is better that 3-4 hours have passed since the last meal, however, a shorter period of time should not force doctors to delay the analysis, especially if myocardial infarction is suspected.

Deciphering the results

Decryption starts from the lab

Usually, it takes about a day to receive the result of the analysis in a planned manner, and about 1-2 hours in an emergency. The primary interpretation is carried out in the laboratory indicating an increase or decrease in the level of LDH, after which the conclusion of the laboratory is interpreted by the attending physician, more often by a general practitioner, cardiologist, pediatrician, or other specialists.

The doctor needs to correlate laboratory results with clinical picture diseases, and then orient with further diagnosis and treatment. For example, in case of suspected myocardial infarction (long-term compressive pain behind the sternum, not relieved by nitroglycerin), emergency doctors who arrived at the call immediately begin the primary diagnosis (take an ECG) and primary treatment(aspirin, clopidogrel, heparin, propranolol and morphine if necessary), but blood is also taken for analysis. Subsequently, the patient is taken to the therapeutic or cardiology department, and the blood is transferred to the laboratory to study the level of enzymes, one of which is LDH.

In a planned manner, the doctor does not need to rush, but this does not change the order of his work: an analysis for LDH correlates with the clinic, for example, cirrhosis of the liver or a lung tumor, after which they move on to more complex diagnostic methods (ultrasound, CT, MRI) and treatment.

Enzyme Level Correction

Identification of the cause is the path to a successful correction of the indicator

It is simply impossible to correct the level of LDH without correcting the patient's condition. There are no drugs that directly reduce or increase LDH.

Only timely treatment for the identified pathology can ensure the normalization of the indicator. For example, the appointment of hepatoprotectors for hepatitis or cirrhosis of the liver will reduce damage to the cells of the organ and the release of LDH into the blood. The appointment of surgical, chemical, radiation therapy will lead to the death of the tumor tissue, after which LDH will gradually normalize. In the case of an increase in LDH due to hemolysis, hemotransfusion is necessary, that is, a transfusion of red blood cells and other blood components to the patient if necessary.

A decrease in LDH usually does not require correction.

The role of LDH in the diagnosis of myocardial infarction

LDH is one of the enzymes that respond to necrotic processes in the heart muscle. Below is a table with enzymes and their reaction time to the process.

As can be seen from the table, the very first enzyme that reacts to myocardial infarction is CPK-MB, but it returns to normal one of the first. LDH, in contrast, increases a little later, but rests on high level as long as possible, which is valuable in the late diagnosis of myocardial infarction.

Of course, LDH activity depends on the size and depth of the damaged muscle focus, and the return to normal depends on the reserve of myocardial cells and the start of timely treatment.

In addition to the initial diagnosis of myocardial infarction, LDH makes it possible to distinguish from it an attack of angina pectoris, short-term ischemia of the heart muscle without the formation of necrosis. It was noted that in angina pectoris the level of LDH is normal, which is explained by the preservation of the integrity of myocardial cells.

General information about LDH

Lactate dehydrogenase (LDH) is an important intracellular, zinc-containing enzyme that is present in most organs and tissues. An increase or decrease in the amount of lactate dehydrogenase and its multiple isoenzymes may indicate damage to the integrity or destructive changes in the organs in which they are located.

The main biochemical function of LDH in the human body is the conversion of lactic acid into pyruvic acid. This is due to the specific structure of the enzyme, which allows the hydroxyl group to be cleaved from the lactate molecule, followed by the formation of pyruvate. Pyruvic acid is the key to the tricarboxylic acid cycle, also known as the Krebs cycle. The Krebs cycle is the most important stage in the respiratory processes of almost all cells that use oxygen.

Lactic acid is a dangerous and numerous metabolite in the body. Thanks to the enzyme LDH, lactate is used to break down glucose, which then produces a large amount of energy. The generated energy is used by the body to carry out vital biochemical reactions and muscle contraction, resulting in the formation of lactic acid.

With a lack of oxygen in the human body, the reverse transformation of lactate into pyruvic acid can occur. In yeast, which are anaerobic organisms, lactate is converted into ethyl alcohol. This phenomenon is known as fermentation and is actively used in industry and everyday life.

If there is an insufficient amount of oxygen in the human body, the enzyme lactate dehydrogenase accumulates, which leads to fatal changes in cell metabolism and disruption of the integrity of its membrane. The release of the contents of the cell into the bloodstream leads to an increase in the amount of LDH, which doctors will detect in a biochemical blood test. Lactate dehydrogenase is one of the most important indicators of cell destruction of tissues and organs in which it is located.

Types of LDH

1. LDH-1. Found in heart muscle and brain cells
2. LDH-2. Localized in the tissues of the kidney and spleen
3. LDH-3. Most commonly found in the lungs, thyroid gland, pancreas, and adrenal glands
4. LDH-4. Is characteristic of the placenta and male sex hormones
5. LDH-5. Marker of destructive lesions muscle tissue and liver.

Most often, the first isoenzyme is found in acute myocardial injury, known as a heart attack. These phenomena are used to diagnose myocardial infarction, which helps to significantly reduce mortality. With myocardial infarction, LDH-1 rises after 12-16 hours.

At the present time for rapid diagnosis myocardial injury using troponin tests. They are more specific and appear faster in the blood. Troponin tests become positive in the first hours after the onset of necrotic changes in the heart muscle.

An increase in the number of isoenzymes 2, 3 and 4 in the bloodstream will indicate not only destructive changes in the relevant organs, but also a massive death of platelets. These changes may indicate that the patient has pulmonary embolism. Since the mortality in PE is very high, timely diagnosis will help save the patient's life.

An increase in the amount of the fifth isoenzyme of lactate dehydrogenase (LDH) in most cases occurs in the acute phase of viral hepatitis.

How is LDH determined?

To determine LDH and its isoenzymes, the patient's venous blood is examined. There is no special preparation for donating blood for LDH, since this indicator is not specific.

To conduct an adequate study, doctors recommend several general rules:

1. Blood sampling from the patient is done on an empty stomach. It is desirable that the procedure was carried out before 10-11 am. A specific diet does not need to be followed. It is necessary not to eat 8 hours before the proposed trip to the hospital. If this rule is violated, then the blood will clot and will be unsuitable for further research.
2. Stop smoking the day before the test
3. A few days before going to the laboratory, you must refuse to take alcoholic beverages. Alcohol affects the coagulation and rheological properties of blood. Also, when drinking alcohol, the amount of LDH-5 increases, due to necrosis of liver cells.
4. On the day of blood donation, you should refuse to take medicines. Acetylsalicylic acid, contraceptives, antidepressants can significantly change the coagulation properties of the blood, which will make it impossible to conduct a study. If the patient has taken some medicine, he should inform the doctor about it. Most likely, medical staff will reschedule the blood draw to another day.
5. Significant physical activity on the eve of the study significantly changes blood counts, which leads to an inadequate result.

Which specialist pays attention to this parameter?

Studies of lactate dehydrogenase is not a specific indicator of the disease. This analysis is used as an auxiliary and indicates the destruction of cells or inflammatory process. Therapist, oncologist, cardiologist and doctor general practice- family medicine may prescribe this analysis if you suspect the development of the disease based on symptoms and anamnesis.

In such cases, the doctor prescribes lactate dehydrogenase studies:

1. For pain different nature behind the chest. Used as a differential parameter. Such pain can cause pulmonary infarction, myocardial infarction, angina pectoris and calmness, gastroesophageal reflex disease. Increases in the first isoenzyme will indicate the development of a myocardial infarction in a patient
2. At malignant tumors the oncologist prescribes this analysis to monitor the dynamics of the development and course of the disease. Also, a decrease in the LDH enzyme will indicate the success of treatment and the regression of the tumor process. Not so long ago, scientists synthesized a substance that blocks the production of lactate dehydrogenase. This leads to the accumulation of lactic acid inside the cell and its death. If this substance is introduced into the location of the development of the tumor process, then cancer cells will die. It has been experimentally proven that such a drug is effective only in the first stages of the development of the tumor process.
3. When staging previously diagnosed diseases of the kidneys and liver
4. When analyzing the state of muscle tissue
5. When monitoring the condition of a patient with chronic diseases
6. When examining the whole body for preventive purposes
7. To determine the type of anemia

LDH values

Based on changes in the concentration of LDH in the blood, it is impossible to make a diagnosis. Only a doctor can interpret and draw any conclusions. The normal concentration of LDH in the blood depends on the age, gender and condition of the patient. Doctors in their work use the following reference values:

1. From the birth of a child to the first year, this parameter is 451 units per liter
2. From the first to the third year of life, this value is 344 units per liter
3. From 3 to 6 years, the norm will correspond to 314 units per liter
4. At 6-12 years old, the norm is 332 units per liter
5. From 12 to 17 years old, the norm will be in the range of 279 units per liter
6. 17 years and older, the reference value of the norm is already distributed depending on the sex of the subject. For male patients, these values ​​will be at the level of 135-225 units per liter. For the female - 135-214 units per liter

For pregnant women and professional athletes, LDH reference values ​​are higher than in the general population.

Changes in LDH levels in the bloodstream

The cause of an increase in the amount of lactate dehydrogenase in the blood may be the following pathological conditions:

• myocardial infarction
• Viral hepatosis
• Cirrhotic changes in the liver
• Oncological diseases
• Acute pancreatitis
• kidney disease
• anemia
• Traumatic injuries
• Muscle tissue disease
• Functional disorders of the cardiovascular and respiratory systems
• Lymphoma
• Leukemia
• Myositis and polymyositis
• Inflammation of the lungs
• Phlebothrombosis of the lower limb
• AIDS virus
• Sepsis
• Acute necrotic process

The amount of lactate dehydrogenase decreases with successful treatment of oncological pathology, hemolytic anemia, and lymphomas. LDH also decreases if the patient has oxalates, urea, and a specific inhibitory enzyme. If the patient was taking medicines, the result will be underestimated. These drugs include: amikacin, ascorbic acid, hydroxyurea, dofibrate, captopril, prednisolone, naltrexone, cefotoxime, antispasmodics.

LDH in cerebrospinal fluid and pleural effusion

An increase in the amount of the enzyme lactate dehydrogenase in the pleural effusion helps doctors differentiate between exudate and transudate. If this figure is more than twice, then this indicates in favor of the exudate, and if it is lower, then this is a transudate. With pleural empyema, the amount of lactate dehydrogenase rises to 1000 units per liter.

In the cerebrospinal fluid, an increase in LDH is found in bacterial meningitis.

Conclusion

The value of the determination of LDH in the blood is not high, due to its low specificity. LDH rises in diseases of the kidneys, liver, heart and characterizes the destruction of their cells.

An analysis for LDH can lead to the idea of ​​\u200b\u200bthe disease. Without additional research diagnosis is impossible.

Common lactate dehydrogenase (LDH) is an intracellular glycolytic enzyme that is involved in the reversible conversion of lactate to pyruvate and is found in most body tissues.

Russian synonyms

Lactic acid dehydrogenase.

SynonymsEnglish

Lactate dehydrogenase, Total, Lactic dehydrogenase, LDH, LD.

Research method

UV kinetic test.

Units

U / l (unit per liter).

What biomaterial can be used for research?

Venous blood.

How to properly prepare for research?

• Do not eat for 12 hours prior to the study.
• Eliminate physical and emotional overstrain 30 minutes before the study.
• Do not smoke for 30 minutes prior to the study.

General information about the study

Lactate dehydrogenase (LDH) is a zinc-containing intracellular enzyme that catalyzes the oxidation of lactic acid to pyruvate and is found in almost all cells of the body. LDH is most active in skeletal muscle, heart muscle, kidney, liver, and red blood cells.

There are five different forms(isoenzymes) LDH, which differ in molecular structure and location in the body. Which of the five prevails depends on the main way of oxidizing glucose - aerobic (to CO 2 and H 2 O) or anaerobic (to lactic acid). Such a difference is due varying degrees relationship of one or another isoenzyme and pyruvic acid. For the myocardium and brain tissue, LDH-1 is the main one, for erythrocytes, platelets, kidney tissue - LDH-1 and LDH-2. In the lungs, spleen, thyroid and pancreas, adrenal glands, lymphocytes, LDH-3 predominates. LDH-4 is found in all tissues with LDH-3, as well as in granulocytes, placenta and male germ cells, which also contain LDH-5. Isoenzyme activity in skeletal muscles (in descending order): LDH-5, LDH-4, LDH-3. For the liver, the LDH-5 isoenzyme is most characteristic, LDH-4 has less activity. Normally, in the blood serum, all fractions of the enzyme are determined with little activity as part of the total indicator - total LDH. Their activity in the blood is distributed as follows: LDH-2 > LDH-1 > LDH-3 > LDH-4 > LDH-5.

In diseases accompanied by tissue damage and cell destruction, LDH activity in the blood increases. In this regard, it is an important marker of tissue destruction. Despite the fact that an increase in enzyme activity 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 tests 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. pain syndrome in chest. In patients with angina, the activity of the enzyme does not change, but in myocardial infarction it begins to increase after 8-10 hours with a maximum in the first 24-48 hours after a heart attack and returns to normal after 10-12 days. An increase in LDH with normal AST activity 1-2 days after chest pain indicates a pulmonary infarction.

In the differential diagnosis of myopathies, this analysis helps to clarify the pathophysiological mechanisms of the disease. Thus, in violation of muscle function associated with neurogenic diseases, LDH does not rise, but when muscles are damaged due to endocrine and metabolic pathologies, LDH activity increases.

The activity of LDH in the blood can increase due to many malignant neoplasms, with effective treatment, it decreases, which is sometimes used for dynamic monitoring of cancer patients.

What is research used for?

• For the diagnosis of acute or chronic tissue damage during a comprehensive examination of the patient.
• For differential diagnosis diseases with severe pain in the chest (myocardial infarction, angina pectoris, pulmonary infarction).
• To detect diseases accompanied by hemolysis of erythrocytes.
• In order to monitor the flow oncological diseases during therapy.
• For the study of pathologies of the liver and kidneys.
• For the diagnosis of lesions of muscle tissue.

When is the study scheduled?

• When acute or chronic damage to tissue and cells in the body is suspected.
• With a comprehensive preventive examination of the patient.
• When observing the course of some chronic diseases(muscular dystrophy, hemolytic anemia, diseases of the liver, kidneys), oncological pathology.

What do the results mean?

Reference values

Reasons for increased activity of lactate dehydrogenase total:

• myocardial infarction,
• pulmonary embolism and pulmonary infarction,
• blood diseases accompanied by hemolysis (hemolytic, pernicious, megaloblastic, sickle cell anemia, erythremia),
• malignant neoplasms various localizations(testicular cancer, liver cancer, lymphoma, bone and liver metastases, etc.),
• leukemia,
• liver pathology (viral and toxic hepatitis, liver cirrhosis, obstructive jaundice, alcoholic disease liver),
• kidney disease (kidney infarction, glomerulonephritis, pyelonephritis),
• muscle pathology (muscular dystrophy, trauma, atrophy),
• bone fractures,
• congestive heart failure, acute coronary insufficiency (without a heart attack), myocarditis (moderate increase in the enzyme),
• Infectious mononucleosis,
• intestinal infarction,
• acute pancreatitis,
• stroke,
• convulsive seizure,
• delirium tremens,
• eclampsia,
• traumatic shock,
• severe conditions accompanied by hypoxia, hyper- and hypothermia,
• burn disease,
• pneumocystis pneumonia,
• premature detachment of the placenta,
• hypothyroidism.

What can influence the result?

The result can be improved by:

• intense physical activity shortly before the study,
• the patient has a prosthetic heart valve (erythrocyte hemolysis due to cell damage by the valve leaflets),
• application electropulse therapy shortly before the study
• hemodialysis (due to the removal of enzyme inhibitors - urea during the procedure),
• a large number of platelets (thrombocytosis),
• some skin diseases
• drugs that increase LDH activity (anesthetics, aspirin, vasopressin, valproic acid, narcotics, procainamide, ethanol, amiodarone, anabolic steroids, verapamil, isotretinoin, captopril, chloramphenicol, codeine, dapsone, diltiazem, interferon-alpha, interleukin-2, some antibacterial and antifungal drugs, non-specific anti-inflammatory drugs, penicillamine, streptokinase, thiopental, furosemide, methotrexate, sulfasalazine, simvastatin, tacrolimus).

Possible reasons for the decrease in the result.

K cellular enzymes are rather nonspecific in terms of examination and identification of pathological processes. Rising and falling indicators are observed in various cases. Sometimes we are talking about dozens of possible diseases. Therefore, specialists have to develop modifications, new diagnostic methods.

LDH in the blood is a special enzyme known as lactate dehydrogenase, and is responsible for energy metabolism at the cellular level: in particular, the breakdown of glucose and the acceleration of the conversion of lactic acid into pyruvic acid.

It is contained in all, without exception, cytological structures, in the tissues of the body. True, in various concentrations. Without it, there can be no normal life as such.

The substance reaches its highest concentration in functionally active, loaded organs. For example, in the liver, heart, lungs. It is also present in blood cells, but in negligible amounts, since their role is completely different.

The study of LDH is carried out as part of a biochemical blood test. There is no need to specifically study the indicators, unless suspicions arise. Then auxiliary, aiming techniques are prescribed.

What is LDH and when is this indicator studied?

Lactate dehydrogenase is responsible for energy metabolism at the cellular level. More specifically, thanks to this substance, two main processes are possible:

• Anoxic breakdown of glucose. It's not the best effective method power generation, but extremely fast. Due to the fact that it is generally possible, the body constantly and without interruption receives even small, but necessary resources.

They are spent on providing basic processes. Conduction of nerve impulses, contraction of muscles, including cardiac, myocardial muscles.

• The second way that lactate dehydrogenase provides is the oxygen breakdown of glucose. True, indirectly. LDH accelerates the conversion of lactic acid to pyruvic acid. Already this substance is responsible for the oxidation of organic sugars. And that means significant energy production.

Actually LDH itself is not consumed during these processes. It remains in the same concentration, inside the cells. This is the result of its chemical structure.

As stated earlier, lactate dehydrogenase is an enzyme. And like all the substances of this series, it is not consumed, but only accelerates biochemical processes. In the case under consideration, we are talking about an increase in the intensity of reactions by dozens of times.

The analysis is excellent for diagnosing pathologies internal organs . In particular, the study can identify such disorders:

• Angina pectoris, heart attack and other disorders of the heart.
• Kidney damage. Pyelonephritis, all kinds of destructive, inflammatory phenomena.
• Lymphadenitis.
• Functional disorders of the spleen. Enlarge it in size.
• Pneumonia. Inflammation of the lungs.
• Myositis. Muscle inflammation. The same applies to dystrophic processes. When the muscles are destroyed.
• Pancreatitis. Other diseases of the pancreas.
• To a lesser extent, the change indicates problems with the hematopoietic system.

Lots of options. But there is one significant difficulty.

LDH in a blood test is a non-specific indicator: indeed, during the breakdown of tissues, cells, it enters the bloodstream and is fixed by laboratory equipment, but it is impossible to say why. Therefore, experts resorted to a trick and studied the enzyme in more detail.

It turned out that despite the generally identical structure, lactate dehydrogenase has specificity depending on where the substance is located and in which cells it is contained.

Modifications are called isoenzymes. There are 5 options in total. They are marked with the corresponding postfix, separated by a hyphen.

• LDH-1. Located in kidney cells of cardio-vascular system. In much smaller quantities, the substance can be found in red blood cells. Sometimes written as HHHH or H4 in the laboratory protocol.
• LDH-2. more specific substance. It is found in the bloodstream if the work of the lymph nodes is disrupted or there are problems with the spleen. The change in the indicator may be indirect. You need to look at other levels of the enzyme.

Labeled as H3M or HHHM in laboratory protocol. These are synonyms. How exactly a particular clinic will reflect the name is a matter of preference and applicable methodology.

• LDH-3. It is located in the cells of the pulmonary system. respiratory structures. Due to the high specificity, it is possible to accurately describe the essence of the problem. Other names are H2M2 or HHMM.
• LDH-4. Penultimate variation. It is located in the structures of the placenta in pregnant women, also in the pancreas. In the organs digestive tract. Other names are HM3 or HMMM.
• LDH-5. Last option. Localized in the liver, musculature of the skeleton (not the heart). Described as M4 or MMMM.

Lactate dehydrogenase isoenzymes are investigated separately, if there is a reason for that. Usually in the case when the overall indicator is increased in biochemical analysis blood. The question of whether a targeted assessment is needed remains at the discretion of specialists.

Preparation and delivery of material

There are no difficulties in terms of preparation. It is enough to follow simple tips.

• Refrain from eating within 12 hours. The analysis is handed over on an empty stomach. Preferably before 9-10.00. During this period, the results will be most accurate.
• For a day or two, alcohol should be excluded. Ethanol, its decay products will inevitably provoke tissue damage. And this will lead to an increase in LDH levels, a false result and, possibly, problems with diagnosis.
• The same goes for the diet. There is no special diet as such. But per day it is important to minimize the amount of products with high content fat. Otherwise, the liver will be overloaded. This will inevitably affect the concentration of the enzyme. A false result will require a repeat analysis.
• For 24 hours refuse and from tobacco. Cigarettes provoke the same problems as alcohol.
• A few hours before the procedure, you should not overexert yourself physically. Intense muscle contraction will lead to a false increase in LHD.
• Finally, you need to consult your doctor about your current treatment. Many medications artificially increase lactate dehydrogenase levels. For example, funds based acetylsalicylic acid. Often also anti-inflammatory drugs. It is advisable to abandon them at least for a day or two. But this is not always possible. It is impossible to cancel drugs on your own.

The procedure as such is no different from a standard blood test.

The patient arrives at the appointed time. AT treatment room donates material from a vein. The sample is placed in a test tube and labelled. Next, the laboratory calculates the concentration of the substance in the serum and gives a conclusion.

On average, it takes 1-2 days to prepare the results. There are no difficulties in terms of evaluation. With the protocol, the conclusion, the patient is recommended to contact the doctor who sent him for analysis.

Tables of norms by age

The concentration of the enzyme depends on the period of life and on the sex of the person. The norm of LDH in women is approximately 20% higher than in men.

Reference values ​​change only in childhood. Then the range stabilizes and does not move any more.

The levels are approximate and refer to the total concentration of the substance in the biochemical analysis. Isoenzymes are also examined as part of advanced diagnostics. Decryption is the prerogative of a specialist.

Reasons for the increase in LDH

If lactate dehydrogenase is elevated, this means that there is a massive destruction of body cells and the release of the enzyme into the blood. An increase in the concentration of a substance is much more common than a decrease.

LDG changes as a result of a number of factors:

• Pathology of the lungs. Inflammation (pneumonia), thrombosis and other disorders. Those during which the organ is destroyed. The reason for the increase in LDH is cell destruction, as a result of which the accumulated reserves of lactate dehydrogenase are released into the bloodstream. Moreover, the degree of violation can be judged by concentration.
• Myocarditis. Myocardial infarction. In the first case, we are talking about an infectious lesion of the muscle layer of the organ. Usually bacterial.

In the second - about the rapid death of cardiomyocyte cells as a result of acute ischemia: malnutrition and respiration.

In both situations, LDH is elevated in a biochemical blood test, but with a heart attack it is much stronger, since the volume of dead tissues is many times larger. The same is possible with severe myocarditis.

• Malignant tumors. It doesn't matter what localization. They grow infiltratively - they grow through healthy tissues, thereby destroying them. Hence the growth of the enzyme. At the same time, malignant cells also have in stock a substance that ensures their energy metabolism.

With a large tumor size, cancerous structures no longer receive enough nutrition and begin to die off on their own, en masse, which increases lactate dehydrogenase even more.

• Hepatitis. A group of diseases characterized by inflammation of the liver. Usually of infectious origin. Less toxic, medicinal. In hepatitis, the concentration of LDH increases within 10-30% of the norm, this is not such a serious increase, but this happens only on early stages. As it progresses, things get worse.
• Cirrhosis of the liver. Serious illness organ. Hepatonecrosis. That is, the death of the cells of the largest gland. In an acute course, the concentration of LHD increases many times right before our eyes. Chronic forms cirrhosis are less aggressive in this regard. Therefore, the growth is smooth.
• Inflammatory lesions of the kidneys. Pyelonephritis, glomerulonephritis. That is, both infectious and autoimmune. Not tied to etiology. Also, other diseases of the structures of the urinary tract. The list is not limited to these two.

• Pancreatitis. Inflammation of the pancreas.

• infectious processes. Mostly associated with damage by pyogenic flora (for example, staphylococcus aureus) or herpetic agents.

The classic situation is mononucleosis. The disease caused Epstein-Barr virus. Or cytomegaly, a type 5 herpes lesion.

It is difficult to say how much the indicator is growing. It all depends on the degree of disruption of the body and the intensity of the immune response. There is not even an approximate calculation.

• Massive burns. To a certain extent, the enzyme is also found in the cells of the dermis, as well as in the subcutaneous fat. If muscles are also affected, the situation becomes extremely threatening. The larger the area of ​​damage, the more serious the LDH deviations from the norm.
• Problems with the placenta. Detachment, insufficiency.
• Excess synthesis of hormones thyroid gland. Hyperfunction.
• Muscular atrophy. For example, with prolonged fasting. When the body begins to utilize its own muscles. Or against the background of a long period of immobilization. In bedridden patients.

Among other things, based on the dynamics, conclusions can be drawn about the nature of the disease: how it proceeds and how effective the therapy is.

There are also situational culprits. They, as a rule, do not relate to diseases and are due to the subjective actions of patients.

For example:

• Alcohol consumption in large quantities.
• Physical overload.
• Smoking on the eve of the study.
• Taking certain medications.

And others. Decoding should be entrusted to a doctor. Usually, elevated lactate dehydrogenase means that there are organic problems.

Reasons for the decline in performance

It occurs several times less frequently. The culprits may be:

• Irrational nutrition. As a rule, leads to the accumulation of salts of oxalic acid. Oxalates (properly named substances) inhibit the normal enzymatic activity of lactate dehydrogenase.

Not the entire volume of the compound is involved in catalysis (accelerates reactions). Therefore, there will be deviations in the analysis. Since the calculation methods are precisely based on the interaction of special reagents and the LDH enzyme.

To obtain more accurate data, the patient should be told about the nature of the diet. Separately, it is important to check the state of metabolism.

• Kidney diseases. Oxalates are normally excreted in the urine. If the excretory system does not work efficiently enough, there is a reverse absorption of substances, their penetration into the bloodstream. The concentration of LDH is reduced in nephritis, kidney failure in the phase of sub- and decompensation. The more running the process, the worse things are.
• Metabolic disorders. On the general level. For a variety of reasons. Decreased LDH in the blood occurs when the pituitary gland, hypothalamus, diabetes, problems with the adrenal glands, disorders of the thyroid gland (in which the synthesis of hormones decreases), etc.
• Taking certain medications. Antibiotics (of any type) and hormonal medications have particular activity against lactate dehydrogenase. To a lesser extent, vitamin C. Vitamin C. To draw any conclusions, first the drug is canceled, then the biochemical study is repeated. If the indicators are restored, the medicines are to blame. The course of therapy is being reviewed.
• Treatment provided. If you lower LDH - this is the desired result of the correction. If a patient receives a special course and the enzyme level drops, this is exactly what the specialist is counting on. If there is any doubt, auxiliary diagnostic measures are prescribed.

Low LDH levels are not as common. But this is a significant result. Therefore, it is somewhat easier for doctors to interpret such deviations.

Additional Research

It is not enough to detect changes in enzyme concentration. To say something concrete, a thorough and comprehensive diagnosis is required. Additional methods include:

• Consultations of specialized specialists. Depending on which isoenzyme is outside the reference values. For suspected problems with the liver - a gastroenterologist. The same applies to the pancreas. If most likely the violation affects the heart - you need the help of a cardiologist and so on. At the initial consultation, the doctor identifies complaints, compiles a list of manifestations and puts forward hypotheses. They need to be checked.
• Collection of anamnesis. Treatment provided. Currently used drugs, past diseases. Also the nature of nutrition, daily activities.
• Ultrasound of organs abdominal cavity. More doctors are interested in the state of the liver and pancreas itself.
• If necessary, in order to study the functional safety of the largest gland, scintigraphy is prescribed. Radioisotope research. After the injection of the iodine preparation, the patient is placed under a special sensor. According to the dynamics of excretion, accumulation, conclusions are drawn about the safety of the organ. His ability to work.
• Electrocardiography. To detect functional disorders of the heart.
• ECHO-KG. Ultrasound modification. In this case, the muscular organ is examined. It is possible to draw conclusions about the nature of pathologies. If there are any at all. The technique is especially important against the background of a heart attack or angina pectoris. For routine screening in coronary artery disease.
• Electromyography. Checking the contractility and condition of the muscles.
• Hormone tests. Doctors are interested in the levels of T3, T4, TSH, cortisol, adrenaline, and others. That is, the substances of the thyroid gland, pituitary gland and adrenal glands.
• Be sure to conduct special tests to detect diabetes. At the very least, a blood sugar test. Possibly provocative. When the patient is offered to drink a concentrated glucose solution.
• An MRI or CT scan is ordered as needed. As part of the diagnosis of complex organic pathologies or tumors.

Quite a lot of research. Assign those that will be useful in a particular case and help to refute or confirm previously put forward hypotheses.

The LDH test is an effective and simple way of initial examination. The results allow us to determine the direction of further diagnostics and understand which organ is under attack.

To obtain comprehensive data, you need to carry out a set of activities and evaluate the results in the system.

Blood lactate dehydrogenase (LDH) is a laboratory test with low specificity. However, its deviation from the norm is a sufficient condition for a comprehensive examination of the patient. It is necessary for the primary diagnosis of pathologies in the work of the heart, lungs, kidneys, various oncopathologies and destruction of muscle tissue in humans.

In order to understand the purpose for which the analysis is prescribed, you should first understand - what is LDH in a biochemical blood test?

Lactate dehydrogenase (LDH) in the blood is an enzyme localized inside cells. The composition necessarily includes zinc ions. Its main function is to catalyze the oxidation of lactic acid to pyruvate. Almost all cells in the human body contain the enzyme LDH. The maximum concentration is observed in skeletal (9000 units/g) and cardiac (25000 units/g) muscles, as well as in the kidneys (15000 units/g), lungs (9500 units/g) and liver (9000 units/g).

In case of cell damage, an active release of the enzyme into the bloodstream occurs. Blood cells also contain LDH, however, their content is negligible. That is why even with a slight destruction of the tissues of any of the organs, there is a sharp increase in the level of LDH in the blood serum, which is used to diagnose various diseases. This fact allows us to classify the blood test for LDH as highly sensitive, but low specific criteria.

Enzyme isoforms

From the point of view of the information content of the obtained results, LDH isoforms are more preferable due to an increase in the level of specificity. There are 5 isoforms of the enzyme with characteristic physicochemical properties.

Indications for the study

A doctor can write out a referral for a biochemical analysis of blood serum in order to determine the level of LDH if:

• the patient has symptoms of chronic or acute damage to the integrity of cells and tissues;
• a person feels severe pain in the chest area, the cause of which may be myocardial infarction or angina pectoris;
• flow control needed chronic pathologies including oncology;
• large-scale screening of human health.

The norm of LDH in the blood

Any interpretation of the results should be carried out exclusively by a specialist. In view of the low specificity of the criterion under consideration, its isolated use for the final diagnosis of the disease is prohibited. Indicators normal concentration LDH in adults and children in the blood are shown in the table.

It should be noted that LDH levels are normally higher in men than in women. Deviation from the reference (normal) values ​​up or down indicates the development of the pathological process.

The value of indicators of LDH isoenzymes

The activity of isoenzymes is determined by the degree of inactivation by urea. It has been established that the level of inhibition of the enzymatic activity of human serum by urea ranges from 26 to 36%. This indicator is considered as a standard value for comparing the inhibitory properties of the five fractions of isoenzymes.

The table shows that each fraction has its own level of inhibition. Based on the known data on the priority organ for the synthesis of each isoenzyme, and the results of the analyzes, it is possible to determine with a high degree of probability the organ in which the disease develops.

Deciphering the results: reasons for the downgrade

It is noted that the level of LDH is lowered in the following cases:

• the presence of oxalates (salts and esters of oxalic acid) and urea in the patient, which weaken the enzymatic activity of LDH;
• taking medications that reduce the work of the enzyme (antibiotics, ascorbic acid);
• the effectiveness of the chosen treatment tactics, leading to the normalization of the value of the criterion under consideration.

Causes of an increase in LDH in a biochemical blood test

The criterion under consideration may deviate from normal values ​​in a number of different diseases. The reasons for the increase in the concentration of lactate dehydrogenesis may be:

• myocardial infarction, accompanied by ischemic necrosis of the middle layer of the muscular tissue of the heart;
• blockage of a lung artery by a thrombus or pulmonary infarction;
• pathologies of the blood, which are characterized by the destruction of red blood cells ( different kinds anemia, hemolysis, severe intoxication);
• malignant tumors affecting various bodies and tissues, often accompanied by metastasis;
• violations in the liver against the background of chronic and acute hepatitis, Gospel disease or alcohol intoxication;
• kidney pathology (glomerular nephritis, pyelonephritis);
• atrophy or injury of muscle tissue;
• open and closed fractures;
• congestive heart or coronary insufficiency;
• inflammation of the heart muscle tissue;
• mononucleosis, viral etiology;
• acute attack of pancreatitis;
• convulsive seizures;
• alcoholic delirium (mental abnormalities against the background of a sharp withdrawal of alcohol);
• burn disease;
• abruption of the placenta ahead of time;
• hyperthyroidism.

When identifying the causes of an increase in LDH in women and men, it is necessary to exclude the influence of factors that can lead to unreliable results:

• incorrect blood sampling, as a result of which erythrocytes are destroyed in the test tube (hemolysis);
• neglect of the rules for preparing for the delivery of biomaterial: physical and emotional stress, smoking, alcohol, improper diet;
• the use of treatment methods, accompanied by electrical stimulation of the patient a week before the analysis;
• an excess of platelets in the blood;
• taking medications that activate the enzyme system.

Normalization of LDH levels in the blood

Patients often ask the question - how to reduce the level of the enzyme? To do this, it is necessary to initially establish the exact cause of the increase in LDH. Only when the disease that was the cause is eliminated, it is possible to return the indicator to normal values. Therapy for each of the pathologies has its own characteristics:

• after the first signs of myocardial infarction, a person needs first aid. Any delay in treatment can lead to death and serious complications. In order to assess the risk of relapse, a control measurement of the level of LDH is carried out, which, with adequate therapy, should return to normal;
• in case of anemia provoked by iron deficiency, the patient's nutrition is corrected, and iron-containing preparations are prescribed. A favorable outcome is considered to be an increase in hemoglobin levels and a decrease in LDH;
• in oncopathology, large-scale patient screening is necessary to assess the size of the tumor, the presence of metastases, and the degree of organ damage. At the same time, the evaluation of the effectiveness of treatment includes an analysis for LDH and the main tumor markers. The lack of positive dynamics, expressed in a decrease in the considered criteria, is the reason for transferring the patient to more aggressive methods of treatment;
• when acute pancreatitis it is necessary to place the patient in a round-the-clock hospital. Treatment includes droppers with painkillers, antibacterial and anti-inflammatory drugs. As the patient's condition improves, all biochemical parameters return to normal.

How is LDH analyzed?

To assess the level of LDH and its enzymatic activity, 2 groups of methods are used:

• spectrophotometric, the essence of which is to determine the difference in the absorption spectra of the oxidized form of NAD (a coenzyme of all living cells) from the reduced one;
• colorimetric, subdivided into dinitrophenylhydrazine - determining the concentration of pyruvate, and redox indicator - identifying certain molecules using indicators that change color.

An optical test is used as standards for determining the enzymatic activity of LDH, and electrophoresis is used for isoenzymes. When issuing the results of the analysis, the laboratory must indicate the chosen method.

How to prepare for the study

Preparation for the delivery of the analysis is necessary to obtain the most reliable and accurate results. The biological material is venous blood collected from the cubital vein at the elbow. Recommendations before analysis:

• blood is given strictly on an empty stomach, for 1 day it is necessary to exclude fatty and fried foods from the diet;
• it is strictly forbidden to drink juice, tea and coffee 12 hours before sampling the biomaterial, it is allowed pure water without gas;
• no smoking for 30 minutes;
• refrain from drinking alcohol for at least 48 hours medications. If it is impossible to cancel any drugs, notify the laboratory employee about their intake;
• limit physical and emotional stress in 1 hour.

findings

Summing up, it must be emphasized:

• LDH in a biochemical blood test is a low-specific criterion that suggests a number of diseases. To clarify the diagnosis, it is necessary to conduct additional laboratory and instrumental examinations;
• when deciphering the results, it is important to take into account that the reference value for a child and an adult is different;
• in the case of necrosis and infarction, which are characterized by cell destruction, it is recommended to repeat the analysis after acute stage. This is necessary to assess the degree of tissue destruction and the severity of the pathology;
• identification of the degree of activity of enzyme isoforms allows you to clarify the location of the pathology.

Graduated specialist, in 2014 she graduated with honors from Orenburg State University with a degree in microbiology. Postgraduate graduate of FGBOU VO Orenburg State Agrarian University.

In 2015 at the Institute of Cellular and Intracellular Symbiosis of the Ural Branch of the Russian Academy of Sciences underwent advanced training for additional professional program"Bacteriology".

Laureate of the All-Russian competition for the best scientific work in the nomination "Biological Sciences" in 2017.