What does LDH show in a blood test? LDH in blood biochemistry: increased, normal, what it is. When LDH is low

The LDH (lactate dehydrogenase) test is a nonspecific 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 bacterial ones. Therefore, the level of LDH in the blood is a general indicator of tissue and cellular damage. Sometimes the concentration of a substance is assessed using cerebrospinal or pulmonary fluid in the presence of certain diseases.

The importance of the enzyme in the body

Interest in what LDH is in a biochemical blood test is associated primarily with myocardial infarction. Previously, this test was used to diagnose and monitor damage to cardiac 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. Typically, the transcript of a biochemical blood test contains this indicator. Lactate dehydrogenase in the blood is an important enzyme involved in the reactions:

Glucose oxidation;

Lactic acid production.

The peculiarity of the enzyme is that it does not accumulate in cells, but is completely broken down and excreted. LDH is essential for converting glucose into energy for the functioning of all cells in the body. The reaction is mediated by oxygen, which helps break down glucose into water, carbon dioxide and energy. Without oxygen, energy production decreases by 20 times and lactic acid accumulates. The enzyme LDH is necessary for its oxidation and return to glucose metabolism. Unlike healthy cells, cancerous tumors feed without oxygen.

When is the test prescribed?

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

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

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

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

Acute or chronic tissue damage;

Progression of anemia and severe infection;

Courses of cancer after chemotherapy, leukemia, melanoma, neuroblastoma. High values ​​indicate poor prognosis for patient survival.

The doctor prescribes determination of LDH levels in other body fluids:

To distinguish between bacterial and viral meningitis by analyzing cerebrospinal fluid.

To identify the cause of the accumulation of fluid in the chest or abdomen (pleural, peritoneal and pericardial fluids) due to trauma and inflammation or due to an imbalance of 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 much fatty or protein foods.

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

Intense training the day before can lead to an increase in the enzyme, as it increases energy expenditure and the need for the breakdown of glucose.

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

Blood samples produce false positive results. Violation of the rules for storing samples and rough processing affect the accuracy.

With increased platelet count, serum LDH level also increases and does not show the real picture.

During hospitalization with suspected myocardial infarction and acute pancreatitis, LDH analysis is performed without taking into account the recommendations. Often, the LDH indicator is used to assess the dynamics of the disease and the patient’s recovery.

Norm of LDH in the body and interpretation of the analysis

When testing blood, the norm is usually indicated in units/l, which means one 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 norm is considered to be within 430 units/l.

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

Based on the identified marker, it is impossible to determine which cells were damaged. Therefore, when deciphering LDH, it is necessary to know what its isoenzymes are. Some laboratories conduct additional tests that determine several forms of the 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 lung tissue, endocrine glands and adrenal glands;

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

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

Deciphering biochemistry for increased 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 elevated. Hypoxia, shock and burns are accompanied by cell death, which shows an increase in LDH. Caffeine also affects the amount of enzyme in the blood.

The dynamics of the first isoenzyme are 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 increases relative to LDH-2, a heart attack is diagnosed. Typically, the LDH level in the blood is exceeded 12-24 hours after damage to heart tissue and for two days in 80% of cases. A normal LDH-1/LDH-2 ratio is reliable evidence that there was no attack. The ratio of total LDH to LDH-1 is called hydroxybutyrate dehydrogenase. Therefore, during a heart attack:

The LDH/GBDG figure is reduced (less than 1.30);

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

On the first day, myocardial infarction is diagnosed by the creatine kinase indicator, 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/GBDG figure - up to 1.3 and below;

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

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

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

Most often, LDH is elevated due to the destruction of tissue of the liver and kidney parenchyma, and the death of platelets and red blood cells.

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

With anemia, red blood cells are destroyed, which releases large amounts 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 one to suspect pathology and refer the patient to identify tumor markers.

Along with the LDH level 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 diseases:

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

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

The reasons that lactate dehydrogenase is elevated are varied: HIV infection, sepsis, acute kidney disease, infarction of the intestines and lungs, bone fractures, rash on the body.

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

General lactate dehydrogenase (LDH) is a zinc-containing intracellular enzyme that plays a role in lactate synthesis. It is found almost throughout the body, most commonly in the liver, muscle tissue and heart. LDH has 5 variations, differing in structure and localization:

1. LDH-1 is mostly located in brain tissue and heart muscle;
2. LDH-1 and LDH-2 are localized in blood cells and kidneys;
3. LDH-3 is present in muscles, spleen, adrenal glands, lungs, pancreas;
4. LDH-4 has the same locations as LDH-3, in addition it is found in the placenta, granulocytes, liver and sperm;
5. LDH-5 is found in muscles, in liver cells and in all organs where LDH-4 is localized.

When cells are fully supplied with oxygen, Lactate dehydrogenase is not stored in the body, but breaks down into neutral substances and is released naturally. But with certain disorders leading to cell splitting, its amount may increase. An increase in the concentration of lactate dehydrogenase may be evidence of various pathologies.

Norm of LDH in the blood

There are specific limits for normal LDH concentrations. Immediately after birth (up to 4 days), an LDH level of up to 775 U/l is considered normal. In newborns, the normal level of enzyme in the blood will not exceed 2000 units per liter of blood. In children under 2 years of age, the enzyme level should not exceed 430 U/l, from 2 to 12 years old - 295 U/l. In adults, the amount of LDH decreases significantly and has gender differences: in women the number 135-214 U/l is taken as the norm, and in men - 135-225 U/l.

When is an LDH test required?

As a rule, doctors refer for an analysis of the concentration of LDH in the blood if they suspect many diseases caused by hypoxia or cell breakdown: anemia, myocardial destruction, tumors, pathologies in the liver, and others. With the help of this study, it is possible to identify any abnormalities in the structure of tissues and recognize the disease in time.

Determination of LDH levels

The blood is tested for LDH content using a special technique called the “UV test”. Blood is taken from a vein in the morning (before 10) and on an empty stomach. The resulting substance is then centrifuged to separate the serum from the plasma. It is very important that the serum is clean, without traces of red blood cell breakdown, otherwise the result may be incorrect. Attention! It is not advisable to smoke or drink alcohol on the eve of the test. In addition, you should not eat 6-8 hours before the test, and you should limit your intake of protein and fatty foods. Intense sports can also distort the results. The final indicator is also influenced by the medications taken, so it is worth postponing taking medications on the day of the study. Usually, the results of the analysis can be seen already on the 2nd day of the examination.

Important! An increase in LDH levels does not always indicate pathology. There are physiological reasons for an increase in enzyme levels, such as pregnancy, infancy or increased physical activity.

When LDH is elevated

An increase in LDH concentration occurs in the following pathologies:

• stroke
• myocardial, intestinal or lung infarction
• pulmonary failure
• hypoxia
• acute pancreatitis
• pancreatic diseases
• low blood pressure
• diseases that affect the hepatobiliary complex
• cancer of the blood, kidneys, testicles, etc.
• cirrhosis of the liver
• jaundice (in the first stages of the disease)
• iron deficiency or pernicious anemia
• eclampsia
• placental abruption
• some fungal diseases
• lymphoma
• hepatitis
• Infectious mononucleosis
• skeletal muscle injuries, traumatic shock
• dystrophic condition
• glomerulonephritis
• leukemia
• oxygen deficiency

To accurately determine where the pathological process occurs, it is necessary to analyze which LDH isoenzyme is elevated.

An increase in LDH-1 or LDH-2 levels most often indicates a heart attack. If the concentration of LDH-1 and LDH-3 is increased, then it can be assumed that the patient is developing muscle tissue atrophy. Excessive activity of LDH-4 and 5 isoenzymes often indicates liver dysfunction, as well as muscle and bone damage. If cancer is suspected, then the greatest attention is paid to the amount of LDH-3, 4 and 5.

Important! Elevated LDH levels can be found in conditions such as:

• alcohol consumption
• psychological stress or increased physical activity
• certain skin diseases
• use of certain medications (most often aspirin, anesthetics, fluorides, oral contraceptives and insulin)
• thrombocytosis

When LDH is low

A decrease in the concentration of lactate dehydrogenase in the blood is typical in the following situations:

• consumption of large amounts of ascorbic acid;
• high levels of oxalic acid salts (oxalates) in urine
• a peculiar reaction to cystotic chemotherapy.

A decrease in LDH is very rare and is not always interpreted as evidence of the presence of disorders in the body.

Ways to lower LDH levels

To reduce the lactate dehydrogenase level, it is necessary to accurately diagnose the cause of its increase and eliminate it. A qualified specialist must be involved in deciphering the analysis results. Treatment of the identified disease will help lower the level of LDH in the blood. Monitoring of lactate dehydrogenase is required when the following diagnoses are detected:

If the patient is diagnosed with anemia, he will be prescribed systematic therapy, including taking iron supplements and a special diet. In this case, it is necessary to periodically conduct a biochemical blood test for LDH in order to ensure the effectiveness of treatment.

It is also necessary to regularly donate blood for LDH during the treatment of acute pancreatitis, since it is by the lactate dehydrogenase indicator that the success of therapy can be monitored.

As a rule, qualified doctors eliminate an attack of inflammation of the pancreas without surgery, and only in the most serious cases is its removal prescribed.

In case of myocardial infarction, it is imperative to start treatment on time. First of all, drug therapy is prescribed to help quickly relieve the attack and normalize blood circulation. During treatment, LDH levels should be strictly monitored.

If cancer is suspected, additional examinations of the patient are required. If this diagnosis is confirmed, emergency measures must be taken. As a rule, preference is given to complex therapy, including surgery, chemotherapy and radiation treatment.

Thus, a biochemical blood test for the content of lactate dehydrogenase will help to timely detect various diseases and pathologies in the human body in the early stages, before symptoms of the disease appear. Fortunately, modern methods of examining the body make it possible to avoid dangerous complications. Moreover, comprehensive diagnostics makes it possible to monitor the course of chronic diseases.

Many tests are used to diagnose various pathological processes. Recently, an indicator such as LDH (lactate dehydrogenase) has often been considered.

In order for an ordinary person to understand its meaning, it is necessary to understand what it is. And also find out why it is being studied, what the danger of an increased or decreased level of LDH in a biochemical blood test may be.

Basic information

Lactate dehydrogenase belongs to the class of oxidoreductases and is an essential enzyme that participates in the oxidation of glucose and the formation of lactic acid. Its peculiarity is that it does not accumulate in cells.

The enzyme undergoes complete breakdown and excretion.

The mediator in this process is oxygen, due to which glucose is decomposed into water, energy and carbon dioxide. In the absence of oxygen, energy production decreases by 20 times, which leads to the accumulation of lactic acid.

Unlike healthy cells, cancer cells can feed without oxygen.

Classification

LDH can be divided into isoenzymes that have differences in composition or are found in one specific organ.

Lactate dehydrogenase is classified into several types depending on the organs in which it is present:

• LDH-1 - in the brain and heart;
• 2 - in the blood composition (platelets and erythrocytes) and liver;
• 3 - in skeletal muscles, lungs, pancreas and thyroid glands, adrenal glands and spleen;
• 4 and 5 - in the same organs that are named in the previous paragraph, plus in the liver, placenta, male germ cells, granulocytes.

Depending on the type of LDH, the activity of the enzyme in the blood may differ slightly.

Norm for children and adults

Depending on gender and age category, the norm of the indicator in the blood will be different.

LDH levels are presented in the table below.

As can be seen, children at birth have higher values ​​than adults. With age, the child's norm decreases.

The high value in men is explained by the fact that they are more susceptible to intense physical activity.

In women during pregnancy, values ​​may also exceed the norm. Before donating blood for biochemistry, it is imperative to inform a specialist about this.

When is a test ordered?

It is required to be done when donating blood fluid for biochemistry. It is prescribed not only for almost any disease, but also for preventive purposes.

Close attention to this indicator is paid if there are suspicions of such pathological processes as:

1. Anemia. As the disease progresses, red blood cells are destroyed more rapidly, which leads to an increase in LDH. Indications for analysis in this case will be the following symptoms: pale skin, tinnitus, dizziness.
2. Myocardial infarction. If the heart muscle is destroyed, then the indicator has quite high values.
3. Oncological pathologies.
4. Acute or chronic tissue damage.

In addition, in some cases, determination of the amount of LDH in fluids of other organs may be prescribed.. This is necessary so that, for example, the study of cerebrospinal fluid can differentiate between viral and bacterial meningitis.

Reasons for the increase

LDH activity increases with the development of almost any disease accompanied by inflammatory processes and cell death. Among the reasons for the increase in the indicator are the following:

1. Myocardial infarction in the acute phase.
2. Functional failure of the vascular and cardiac systems, lungs. Malfunctions of the heart lead to circulatory disorders, the appearance of congestive symptoms and activation of LDH fractions 4 and 5.
3. Inflammation of the lungs, liver and kidney parenchyma.
4. Hemolytic and pernicious anemia.
5. , pulmonary embolism.
6. Viral hepatitis during exacerbation. While in the chronic form of the pathology, the LDH level does not go beyond normal limits.
7. Tumor formations of a malignant nature, especially with metastases, the location of which is the liver.
8. Hematological diseases, for example, granulocytosis, anemia, the development of which was preceded by a lack of vitamin B12 or folic acid deficiency.
9. Massive platelet destruction. The main reason for this pathological condition is blood transfusions.
10. Pathologies of the musculoskeletal system. First of all, this applies to damage to the skeletal muscles (atrophy in the initial stages, various injuries).

Determination of the glycolytic enzyme is very important in the diagnosis of myocardial infarction.

Lactate dehydrogenase may also increase for other reasons. These include:

• megaloblastic anemia;
• conditions in which increased destruction of the cellular structure occurs (acute necrotic processes);
• damage to the kidney parenchyma;
• tumors localized in the glands of the reproductive system of men and women.

Thus, the main reasons for the increase in enzymes in the blood serum are pathologies in which the cells of the kidney and liver parenchyma, as well as erythrocytes and platelets are destroyed.

Reasons for the drop in the indicator

If LDH is low, which is extremely rare, the following factors may contribute to this:

• taking ascorbic acid, Metronidazole and other medications for a long time;
• mutations at the gene level;
• treatment of anemia, cancer, leukemia and lymphoma.

In addition, a large amount of oxalates and urea in the human body can provoke a decrease in value, which occurs in the presence of stones in the kidneys and urinary tract.

Symptoms of high and low values

As a rule, an increase or decrease in lactate dehydrogenase levels is not accompanied by specific symptoms. Depending on what could trigger the change in values ​​in the patient, there may be symptoms such as:

• pain in the heart area;
• unstable blood pressure and pulse;
• headache;
• drowsiness;
• general weakness, decreased performance;
• heat.

Necessary tests

To determine the concentration of LDH in the blood fluid, a biochemical analysis is performed. The biomaterial is taken directly from the vein. However, in order for the results to be as true as possible, it is necessary to prepare well for the procedure.

Preparation

Before conducting a study, experts advise performing some simple steps that will increase its accuracy and information content. As numerous practice shows, changing test results is not difficult, but the consequences can be very dire.

When receiving unreliable information, as a rule, an incorrect diagnosis is made and inadequate therapeutic measures are taken that do not bring effective results. We can say that the preparatory stage is a mandatory procedure before analysis.

• do not eat food for 12 hours before the test;
• do not smoke for at least an hour;
• avoid physical activity;
• eliminate emotional turmoil and stress.

In addition, pathological conditions such as:

• hemodialysis;
• dermatological diseases of the skin;
• use of medications;
• thrombocytosis;
• overstrain associated with physical activity.

Immediately before taking the test, the presence of such factors must be notified to a specialist who will decide whether to do tests or not, and will also consider all possible options for error.

Carrying out

In adults, blood is drawn from a vein in the place where the arm is bent. For this, a special needle is used. In children, blood fluid is taken using a lancet.

It is also possible to take it from the heel, earlobe or big toe of the lower limb. After the procedure, a pressure bandage is applied to the sampling site.

The resulting blood is placed on a special glass or in a test tube. In laboratory conditions, the material is lowered into a special device - a centrifuge, where the serum is separated. This determines the concentration of LDH.

Decoding

The interpretation of the results is carried out exclusively by a specialist. Doing this yourself is not recommended.

It is worth remembering: to confirm the presence of any pathological process, determining only LDH is not enough. To create a complete picture, all blood fluid indicators must be assessed.

How to normalize values

If lactate dehydrogenase is elevated, it is first necessary to establish the cause that could provoke this condition. Only after eliminating the underlying disease can the enzyme level be normalized.

Features of therapeutic activities:

1. In case of myocardial infarction, treatment begins immediately after the first signs of the disease appear or after a diagnostic examination. First of all, the patient needs to reduce the load on the heart muscle, ensure the supply of oxygen, and administer a medicine that normalizes blood circulation. During the entire period of therapy, the patient must constantly have blood tested, which will allow monitoring the effectiveness of treatment. With correctly prescribed measures, the value of LDH and other indicators will begin to decrease.
2. If the increase in enzyme concentration was caused by iron deficiency anemia, then the doctor prescribes a special diet, which includes the consumption of foods that contain Fe and vitamin C, special medications that restore the normal level of this element, and walks.
3. For oncological diseases, complex treatment is carried out, which includes taking special medications, chemotherapy and radiation therapy.
4. If LDH is elevated due to acute pancreatitis, painkillers, droppers with albumin or plasma, and digestive enzymes are prescribed. If there is no positive result, the abdominal cavity is washed. In severe cases, surgery is performed, during which the pancreas is removed.

It is important to remember that any medicine can only be prescribed by the attending physician.. Under no circumstances should you do this yourself.

Why is it important to keep the indicator normal?

A significant increase in enzyme levels always indicates the development of a pathological process. In the absence of therapeutic measures or untimely diagnosis, any disease can provoke unpleasant consequences for the patient:

• transition to a chronic form;
• complication of the disease;
• the likelihood of developing a heart attack or stroke increases;
• oncological processes;
• cirrhosis of the liver;
• fatal outcome.

Low LDH values ​​are most often not an indicator of the development of pathology.

An analysis that determines the level of lactate dehydrogenase makes it possible to timely diagnose the presence of any serious disease at the initial stage of its development. Therefore, even for preventive purposes, blood tests must be carried out regularly.

As already mentioned, this is an excellent marker for diagnosing various problems in the body. But what is an LDH biochemical test? This is a blood test that can be used to determine how much lactate dehydrogenase is in the blood. When does such an analysis become necessary?

Before the analysis is carried out, the patient must prepare for it. Your doctor will likely advise you not to take certain medications because they may interfere with the accuracy of your LDH results. We have already determined what it is. However, what medications should not be taken three days before the test?

A biochemical blood test for LDH does not require any special preparation. Like all many other examinations, it should be carried out in the morning on an empty stomach. As far as additional concerns and precautions are concerned, nothing is required. Normal meals are allowed, as always. Physical activity is also allowed, only if you do not overdo it.

In order to conduct a biochemical blood test, it is necessary to take 5-10 ml of blood from a vein on the elbow. In the process of studying the composition of the blood, its composition, quantity and specific gravity of all constituent elements are revealed. All the results of this study and their interpretation are entered into special forms, which list the blood components and their quantitative content.

Then, based on the data obtained in the analysis, the doctor will be able to make the most accurate diagnosis, since the results obtained are compared with established standards for relatively healthy human donors. A blood test, or more precisely the resulting values, can vary greatly in the same person at different ages and with different health conditions.

In most cases, all test indications and criteria cannot have exact reference values. Generally accepted norms fluctuate within a set range. The data obtained is already compared with them: the biochemical analysis showed the norm, or, conversely, whether changes can occur. Any hospital or medical center uses different devices and methods to determine tests, so each individual medical institution sets its own standards for each indicator.

Biochemical analysis carried out approximately simultaneously in different structures may differ. Each clinic that conducts biochemical analysis sets its own requirements and criteria. Therefore, the same analysis indicator, its decoding, is interpreted differently.

First of all, you need to familiarize yourself with the procedure itself (blood test), the method of its implementation and the reason for the appointment. You need to prepare for the tests. It is prohibited to eat or drink anything. It is necessary to take a blood test on an empty stomach, which will further increase the level of accuracy of the results.

Most often, it takes no more than one day to check all blood components. However, the operation can be speeded up. A blood test using this method involves the study of such important blood components as proteins, enzymes, pigments, vitamins, carbohydrates, nitrogenous substances and inorganic elements.

In blood serum, lactate dehydrogenase exists in five isoenzyme varieties - LDH-1, LDH-2, LDH-3, LDH-4, LDH-5. These are special molecular forms of lactate dehydrogenase, which have their own functional specificity. Biochemists depict LDH as a tetramer consisting of a certain number of subunits of two types - M (from the English word “muscle”) and H (from the English word “heart”). Thus, the place of localization of one or another type of LDH is implied - in ordinary muscles and the heart.

Attention! In the practice of biochemical blood analysis, the parameter most often used is total LDH, that is, the generalized, total content of all LDH isofractions.

LDH norms in the LHC

The normal level of LDH in the blood of people of different ages is as follows:

• in a newborn – up to 2000 U/l
• in a child under 2 years old – 425 U/l
• in a child from 2 to 12 years old – 295-300 U/l
• in a child over 12 years old – 250 U/l
• in adults – 235-250 U/l

In cases where one or another LDH isoenzyme is needed as a biochemical marker, they resort to special laboratory tests - the Sevel-Tovarek method, the thermal inhibition method, and the urea inactivation method. The listed tests allow you to measure the level of activity of isoenzymes under different conditions and identify the presence of possible pathology. The table below provides a list of the normal level of isoenzyme activity in each of the listed types of research.

When cells in the human body die, they break down into various biochemical compounds. Almost all of these newly formed substances are toxic or have no utilitarian value for the body, so it removes them beyond its limits with the help of blood (the body’s waste products are delivered to the liver and kidneys).

Lactate dehydrogenase is one such organic compound. It is found in certain tissues of the body, so the presence of it in excess of the norm in the human blood will indicate excessive cell death in a certain part of it. In the case of LDH isofractions, the localization of the phenomenon can be clearly indicated, since each of the isoenzymes has its own specific location:

• Lactate dehydrogenase-1 is found in greatest quantities in the tissues of the myocardium and brain (brain and bone). It is also found in kidney tissues and in the biochemical composition of platelets and red blood cells.
• Lactate dehydrogenase-2 exceeds the level of LDH-1 in erythrocytes and platelets.
• Lactate dehydrogenase-3 is found in the tissues of the spleen and lungs, as well as many glands of the human endocrine system - thyroid, parathyroid, adrenal glands, pancreas.
• Lactate dehydrogenase-4 is a constant companion of LDH-3. It is found in all tissues where this isoenzyme is present, but in smaller quantities. It is also included in the biochemical composition of sperm, granulocytes, and hepatocytes.
• Lactate dehydrogenase-5 exceeds the level of other LDH isoenzymes in the liver and skeletal muscle. The latter also contains less LDH-4 and LDH-3. LDH-5 is found in small amounts in male germ cells.

Attention! An excess of one or another isoenzyme in the blood will be evidence of the development of pathology in this organ.

At the beginning of the article, we already noted that the LDH indicator is used not only to identify pathologies, it is also needed to monitor the patient’s health status. Lactate dehydrogenase is convenient as a clinical marker of the patient’s general health in that it can easily track the dynamics of a person’s recovery.

The most characteristic ailments that are accompanied by an increase in LDH in the blood are the following diseases and pathological phenomena:

• Injuries. An ordinary bruise left after a strong blow is damage to skeletal muscles, and, therefore, a reason for an increase in the level of LDH in the blood. Other injuries can also cause an increase in the level of this enzyme if they affect the organs in which it is present - the heart, liver, brain.
• Lesions of the endocrine glands (pancreas, adrenal glands, thyroid) of various etiologies will increase the LDH content in the blood. Therefore, the enzyme is an excellent marker for monitoring diseases such as pancreatitis, hyperthyroidism, hypothyroidism, Hashimoto's thyroiditis, Addison's disease, cancer.
• Blood diseases. Considering that lactate dehydrogenase is a component of many blood cells, it is not surprising that it is used as a marker for monitoring various blood diseases, primarily leukemia and hematosarcomas.
• Anemia of various types. In anemia, the death rate of blood cells and skeletal muscle cells is higher than normal.
• Liver diseases. Hepatitis of various etiologies causes the death of hepatocytes - liver cells, the biochemical composition of which includes LDH.

Attention! Cirrhosis and liver carcinoma in the advanced stage change the liver tissue so much that it begins to lack LDH, therefore physiological biochemistry does not use this enzyme to monitor the development of these pathologies.

Here everything is much stricter with preparation, preparation for the blood test for LDH. You should not eat anything for twelve hours before the test. Experts also do not advise smoking and drinking drinks containing alcohol, actively engaging in physical exercise and eating a lot. Also, don’t spoil your mood.

Before the examination, the patient needs to calm down and sit in the corridor in front of the office to bring his pulse to normal and calm his heart.

You should also consider the following:

• Stop taking ascorbic acid, anti-seizure medications, and certain medications four days before the test.
• There is no need to take hemodialysis before the procedure.

Doctors warn that a heart valve and possible hematological abnormalities are affecting blood tests.

LDH analysis is a non-specific study. Before cardiologists recognized the troponin test as more effective, blood tests for lactate dehydrogenase levels were prescribed to diagnose heart problems.

Why is it necessary to undergo examination?

A biochemical blood test for lactate (LDH) may be prescribed if the presence of a particular disease is suspected. At the moment, according to historical data in medicine, several main ones can be distinguished:

• these are diseases of the hepatobiliary system;
• after myocardial infarction – carried out in early diagnosis, differential and as monitoring);
• when diagnosing tumors;
• to determine the type of anemia - increased LDH;
• other accompanying diseases.

Preparing for the study

LDH is carried out when there is a suspicion that organs or their systems have been injured. It is tissue damage that provokes an increase in the level of this enzyme in the blood. This is especially true for the tissues of the heart, brain, lungs, kidneys, and skeletal muscles.

If melanoma is suspected, blood LDH is also performed. What does it mean? The fact is that this analysis allows you to identify metastases in organs and lymph nodes. This research method for melanoma cannot be called specific, but it allows you to monitor the patient’s condition in the postoperative period, as well as determine the stage of tumor development. In addition, in the case of effective therapy, the level of the enzyme in the blood decreases, so this marker is used to determine the dynamics of treatment.

A biochemical blood test for lactate is carried out using a special method, which in medicine is written as a UV test (DGKC). As a rule, an analysis of this type should be recorded in the patient's referral. This is not only a special technique and transcript at the end, but also a short medical description.

Most often, in modern and high-quality laboratories, results are given out on the second day, so you won’t have to wait long. It is also worth remembering the quality of the results, because false results are strictly not allowed, especially when LDH is elevated. This can seriously affect the patient's future treatment. Differences in LDH are observed only in children and adults. The gender of the person is not important in this case.

For example, in adults the norm should be in the range from 240 to 480 IU/l. As for children, their differences go up to their years. In children on the first day of life – more than 1327 IU/l; 2-5 days – (amp)lt; 1732 IU/l; 6 days-6 months – (amp)lt; 975 IU/l; 7-12 months – (amp)lt; 1100 IU/l; 1 -3 years – (amp)lt; 850 IU/l;

If the indicator is significantly increased, then it is necessary to pay attention directly to those possible reasons that could cause the increase. A biochemical blood test for lactate is carried out in the same way for adults and children, so it cannot be said that this is a pleasant procedure and it will not hurt for children.

After blood sampling, only serum is extracted for testing, and only from it is it determined whether the patient’s lactate is high or low. There are cases when a biochemical blood test is not ready on the second day after donation
. This is because under the right storage and transportation conditions, blood can be stored for a certain period of time.

The lactate test may be elevated or decreased, and may also be within acceptable limits. If LDH is elevated, this indicates the presence of pernicious or megaloblastic anemia, intense carcinomatosis or hepatitis. Lactate may also be elevated during hypoxia, various shocks, or hyperthermia. The analysis in this case will be negative, since the main indicator is increased and goes beyond the acceptable limits.

Increased activity of lactate dehydrogenase under physiological conditions is observed in pregnant women, newborns, and in persons after intense physical exertion.

Violation of the storage conditions of biomaterial in the laboratory, the patient taking hormonal medications, physical activity and non-compliance with the rules of preparation for the study are a possible reason for elevated LDH levels in a biochemical blood test. If there is any doubt about the accuracy of the results, the doctor will prescribe a repeat test.

Dangers and Consequences

A significant increase in the LGD indicator indicates the presence of a pathological process in the human body
. Lack of treatment or late diagnosis of the disease can lead to unpleasant consequences for the patient. Existing diseases can become severe and chronic, increasing the risk of strokes, heart attacks, and liver pathologies.

If lactate dehydrogenase is elevated, the causes of this phenomenon can be quite varied. This state of affairs can serve as a sign of the development of a large number of pathological processes.

The human body has a rather complex structure, consisting of many organs and systems. At the same time, the coherence of its work is achieved through hormonal adjustments. In turn, the production of such substances occurs in response to certain factors that influence a person. One of these enzymes is LDH, which is involved in the breakdown of glucose and the formation of lactic acid. Under normal conditions, the amount of this hormone is within normal limits, since its excess is eliminated from the body naturally.

Types of enzyme and its role in the human body

Lactate dehydrogenase is one of many enzymes that regulate the functioning of the human body. Its purpose is to help in the processing of glucose, as well as its role in the formation of lactic acid, necessary for full life. In a healthy person, such a hormone is necessarily present in almost all tissues and organs, which once again emphasizes its importance and significance. However, depending on the location of the substance, it is conventionally divided into the following varieties:

• LDH - 1 - heart, red blood cells;
• LDH - 2 - kidneys, spleen;
• LDH - 3 - lungs, thyroid and pancreas, adrenal glands;
• LDH - 4 - placenta, male reproductive cells;
• LDH - 5 - liver, muscles.

Each type of lactate dehydrogenase has its own distinct location, which makes it possible to accurately determine the location of the problem and act on it with the greatest efficiency. In a normal state, a person has a certain amount of this substance in the blood, which, with its help, is distributed to its final destination.

Such a process is natural and has its own specific indicators. At the same time, the formation of certain diseases inevitably leads to an increase in the concentration of LDH in the blood. A similar condition is due to the fact that when certain diseases occur, the body begins to produce an increased dose of the enzyme in the hope of correcting the functions of damaged areas of tissue or organs, which makes it possible to determine their presence in the early stages and allows them to be neutralized with the greatest efficiency.

Norm of quantitative indicators of LDH, dependence on age and gender

Blood lactate dehydrogenase has rather unstable indicators that can vary depending on many factors. In similar conditions, the age of the person is of primary importance, since over time the content of the enzyme in the blood can change. Based on this, today there is a certain classification obtained based on the study of a large number of different cases. When compiling it, data obtained from people of different ages and genders was taken into account, which makes it possible to speak about the fairly high accuracy of this list. A similar decoding looks like this and is expressed in the following ratio µkat/l:

• children from birth to 2 days - 22.1;
• children from 2 to 5 days - 28.9;
• children from 5 days to 6 months - 16.3;
• children from six months to 1 year - 18.3;
• children from 1 to 3 years old - 14.2;
• boys aged 7 to 12 years - 12.7;
• girls aged 7 to 12 years - 9.67;
• boys over 12 years old and adult men - 11.4;
• girls over 12 years old and adult women - 7.27.

These indicators best characterize the influence of a person’s gender and age on the amount of enzyme. At the same time, the level of LDH in the blood in women differs significantly from the concentration of the hormone in men, which has significantly higher levels. This fact is due to differences in the anatomical structure, since male germ cells contain more enzyme than female ones.

Prerequisites for the purpose of research

The LDH test is a fairly specific test, for which a small portion of blood is taken. Its purpose is to determine the amount of enzyme present in the human body and its exact concentration. At the same time, such a blood test can be prescribed if there is a suspicion of the presence of diseases that can cause serious harm to human health:

• study of heart pathologies;
• research of neoplasms;
• diagnosis of muscle pathologies;
• presence of kidney or liver disease.

Such criteria may serve as a basis for conducting a similar study. In turn, an increase in the level of LDH in the blood occurs as a result of the development of an inflammatory process or other formations that have a fundamentally different structure than the main cells of the body. With such a development of events, the immune system, along with a large number of antibodies, helps to increase the production of lactate dehydrogenase. It performs an auxiliary function and is designed to ensure the restoration of the body. In cases where the disease is successfully neutralized, LDH levels return to normal. Otherwise, with a progressive pathological process in the body, a decrease in the concentration of the enzyme does not occur. It is this similar state of affairs that underlies the appropriate analysis designed to determine the exact causes of the formation of pathology and localize it.

Among the diseases that can significantly affect the concentration of LDH in the blood are the following:

• myocardial infarction;
• heart diseases;
• pathological liver damage;
• oncological formations;
• blood diseases;
• violation of muscle tone;
• pancreatitis;
• bone and muscle injuries;
• serious hormonal imbalances.

Such problems may be the cause of a condition where lactate dehydrogenase is elevated, which is a direct consequence of the development of an inflammatory or pathological process caused by the progression of the above diseases. At the same time, diagnostics make it possible to determine their presence at the development stage, allowing for a more optimal impact on the problem and neutralizing it.

Features of analysis and factors that can affect its accuracy

Taking an LDH test is a fairly simple procedure that involves taking a small amount of blood from a vein.

In this case, immediately before the study, it is necessary to adhere to certain rules aimed at increasing its accuracy and information content. As practice shows, it is quite easy to influence the accuracy of testing, but the consequences of this process can be quite serious. They consist of an incorrect diagnosis and subsequent treatment that cannot bring a positive result. Based on this, following the rules before taking a blood test is a prerequisite to guarantee the accuracy of the results and the effectiveness of future therapy. These recommendations look like this:

• limit food intake several hours before testing;
• do not smoke for at least half an hour before testing;
• exclude physical activity;
• avoid emotional turmoil.

It should be remembered that the above factors can change hormonal levels, which can significantly distort the final test result. Therefore, all these requirements are extremely important and require full compliance. In addition, there are some conditions that disrupt the natural balance of enzymes and can affect the accuracy of the tests. They look like this:

• physical stress;
• hemodialysis;
• some skin diseases;
• taking medications;
• thrombocytosis.

Such criteria often lead to distortion of test results, significantly increasing the level of LDH in the blood, which can also cause an incorrect diagnosis and the prescription of completely ineffective treatment. Therefore, before taking tests directly, you must notify your doctor about the presence of such factors. In turn, the specialist will consider the feasibility of conducting tests and the formation of their possible error.