How to conduct a liver examination using laboratory diagnostics?

The liver is an unpaired organ of the abdominal cavity, the largest gland in the human body, which performs a variety of functions.

• The liver neutralizes toxic substances that enter it with blood from the gastrointestinal tract.
• It also synthesizes the most important proteins in the blood and produces glycogen and bile.
• The liver is involved in lymph formation and plays a significant role in metabolism.

Liver tests will tell you whether your liver is functioning correctly or incorrectly.

“Liver tests” are a set of blood tests that are performed in order to diagnose liver and gallbladder pathologies in a patient (in fact, that’s why they got their name). Typically, this test is performed as part of a biochemical blood test. Based on liver tests, the doctor can make a conclusion about how much the liver is affected, whether the disease is acute or chronic, how the treatment affected the liver, how active the process is in cirrhosis or hepatitis.

Liver test analysis includes the following indicators:

• alanine aminotransferase (ALT);
• aspartate aminotransferase (AST);
• total bilirubin and its fractions;
• gamma glutamyl transferase (GGT);
• alkaline phosphatase.
• total protein;

Total protein shows the concentration of protein in the blood. A decrease in this indicator may indicate severe liver disease, since in this case liver cells begin to synthesize less protein.

AST and ALT are enzymes for the synthesis of which the liver is responsible. Separately from each other, changes in the values ​​of these indicators cannot indicate the presence of any pathology; they must be assessed in conjunction with other indicators. Increased AST levels may occur with hepatitis or liver tumors; ALT - in acute liver damage, and this value shifts long before the patient develops the first noticeable symptoms.

An abnormal alkaline phosphatase (ALP) level may indicate the presence of a malignant liver tumor or the development of cholestasis. But we can talk about these diseases only if the values ​​for all enzymes that the liver produces are elevated. If only alkaline phosphatase is elevated, most likely the cause is a disease of some other organ.

Deviation from normal bilirubin is the main indicator that the patient is developing liver failure. However, bilirubin can also change in other diseases, such as hepatitis, blockage of the bile ducts. Deviations in tests can be caused by a strict diet, therapeutic fasting, or poisoning with medications that are toxic to the liver.

There are 2 fractions of bilirubin:

• direct bilirubin;
• indirect bilirubin.

It is important to determine their indicators with an increased value of total bilirubin.
An increase in GGT levels may indicate stagnation of bile, disruption of its outflow, inflammation, tumors and the consequences of excessive alcohol consumption. This enzyme may also be increased by the use of certain medications and drugs.

Indications for the study

There are certain signs that indicate liver damage. As a rule, characteristic symptoms appear already in advanced stages, which complicates the treatment of the pathology. Blood biochemistry to check the liver is prescribed in the following cases:

• Yellowness of the skin. A typical sign of increased bilirubin levels. Yellowness of the skin/eye sclera indicates long-term inflammation.
• Increase in organ size. Deviations can be detected at the initial stage using an ultrasound examination. With a strong enlargement of the organ, the patient experiences a growth of the abdomen against the background of no changes in overall weight.
• Losing weight. For liver pathologies, nausea and refusal to eat are typical, which leads to weight loss.
• Bitter taste in the mouth. Liver disease is characterized by a bitter taste in the mouth, a coated tongue, a thick yellow-brown or white coating, and cracks on the surface of the tongue.

Initial examination of the patient

The initial diagnosis of liver problems is made by a physician who examines the patient and takes a medical history. After this, he writes out a referral for a consultation with a hepatologist or gastroenterologist. Hepatologist is a rather rare specialization that completely concentrates on the work of the hepatobiliary system. Most often, patients with liver problems are referred to a gastroenterologist who deals with the gastrointestinal tract.

The appointment begins with a questioning and subsequent examination of the patient. The doctor recognizes complaints and identifies existing symptoms. During the examination, he palpates and taps the area of ​​the liver to assess its size, density and location.

After this, laboratory tests are selected, including tests to check the liver, additional diagnostic methods that help the doctor accurately diagnose and identify the cause of the patient’s poor health.

Key indicators for liver diseases

The condition of the liver allows you to track certain enzymes. This:

• albumen;
• bilirubin;
• aminotransferases (AST and ALT)
• alkaline phosphatase (ALP)
• glutamate dehydrogenase (GlDH)
• sorbitol dehydrogenase (SDH)
• γ-glutamyltransferase (GGT)
• fructose monophosphate aldolase (FMPA).

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Albumen

It is the main protein produced by liver tissue. A healthy organ produces 150–250 mg/kg albumin within 24 hours. The norm for an adult becomes 35–53 g/l. If the study showed a decrease, then the cause may be: liver failure, chronic hepatitis, cirrhosis.

A decrease in albumin levels is detected before the onset of typical symptoms

Bilirubin

This is a yellow pigment formed as a result of the breakdown of hemoglobin. The resulting indirect bilirubin enters the liver, is neutralized and excreted naturally. Normally, 250–300 mg (total bilirubin) is formed in the human body during the day. Indicators of direct bilirubin are of diagnostic interest. The norm is not higher than 5.1 µm/l.

Exceeding the permissible values ​​in a blood test indicates the following pathologies:

The first symptoms of hepatitis

• inflammation of the gland of viral origin;
• cirrhosis;
• alcohol intoxication;
• cholangitis;
• stones in the bile ducts.

An increase in direct/indirect bilirubin fractions can be caused by:

• toxic/viral inflammation of the gland;
• suppuration, malignant neoplasms in liver tissue;
• cirrhotic organ damage;
• mononucleosis;
• echinococcosis.

Alanine aminotransferase (ALT, AlAT)

ALT norms depend on the gender of the patient: for men – 10–40 units/l, for women – 12–32 units/l. An increase in enzyme levels in the bloodstream can accompany acute hepatitis and obstructive jaundice. An increase in the ALT norm in relation to the permissible one is recorded in cirrhosis and during treatment with hepatotoxic drugs.

An increase in enzyme activity by 4-6 times or more indicates severe liver disease. The deviation is detected before the appearance of typical symptoms - jaundice, pain syndrome and others - in about 1-4 weeks. After the clinical picture develops, elevated ALT levels persist for no longer than 2 weeks, which is a sign of significant organ damage.

Aspartate aminotransferase (AST, AST)

The norm depends on gender: for men – 15–31 units/l, for women – 20–40 units/l. Increased AST activity is recorded in the event of hepatocyte death. Moreover, the more significant the damage to the organ, the higher the enzyme levels. An increase in quantitative indicators also occurs in acute infectious and toxic hepatitis.

Transaminases are an indicator of hepatocyte necrosis

Diagnosis of liver pathologies involves calculating the de Ritis coefficient - the ratio of AST/ALT numbers. Normally, it is equal to or exceeds the number 1.3. A change in numbers towards the lower side of the indicator indicates damage to the organ.

Alkaline phosphatase (ALP)

Enzyme activity depends on gender and age group. In a healthy adult – 30–90 units/l. An increase in alkaline phosphatase occurs in adolescents (up to 400 units/l) and expectant mothers (up to 250 units/l). A significant increase in the alkaline phosphatase level - 10 times or higher - occurs with the development of obstructive jaundice. If the excess is not so significant, one of the forms of hepatitis can be suspected.

Glutamate dehydrogenase (GlDH)

Normally, a biochemical blood test shows a low content of GLDG. The reason is that it is one of the liver enzymes located inside the cell. And an increase in its activity makes it possible to determine the severity of damage to the organ. Increased results indicate the onset of degenerative processes in liver tissue, caused by both external and internal factors.

It can be:

• neoplasms;
• liver metastases;
• toxic substances;
• infectious pathologies.

Calculating the Schmidt coefficient greatly helps in establishing the diagnosis: CS=(AST+ALT)/GlDH. With the development of obstructive jaundice it is in the range of 5–15, for acute hepatitis the figure reaches 30, and for metastases it is approximately 10.

Sorbitol dehydrogenase (SDH)

The norm is an indicator not exceeding 0.4 units/l. If the examination showed an increase in SDH by 10–30 times, then this is a clear sign of acute hepatitis.

γ-glutamyltransferase

In a healthy person, the permissible concentration of γ-glutamyltransferase is: for men – 250–1800 nmol/l*s, for women – 167–1100 nmol/l*s. An increase in enzyme levels is possible with the following problems:

• obstructive jaundice, cholestasis - an increase of 10 times or more is typical for them;
• malignant formations – enzyme activity increases 10–15 times;
• chronic hepatitis – 7 times.

In a blood test, the level of γ-glutamyltransferase is used to distinguish between alcohol and viral damage to liver cells

Fructose monophosphate aldolase (FMPA)

PMPA should be present in the blood only in trace amounts. Determination of this indicator is necessary for diagnosing acute hepatitis. In most cases, it is used to assess liver function in people whose professional activities require direct contact with substances toxic to the liver.

In acute hepatitis of infectious origin, the activity of PMPA increases several tens of times, and with regular exposure to toxic substances - no more than 3 times.

FibroMetr® System

The FibroMetr® system is a non-invasive method for diagnosing liver diseases (using a blood test) and is characterized by high diagnostic efficiency. The method allows you to assess the severity of inflammation, the stage of fibrosis and cirrhosis of the liver.

FibroMetr® can be successfully used for preventive examination, diagnosis of disease, dynamic observation and control of therapy. In some cases, diagnosing liver diseases using the FibroMetr® system may be an alternative to performing a needle biopsy of the liver.

You can undergo a comprehensive diagnosis of liver diseases using the unique FibroMetr® system (BioLiveScale, France) in the CMD laboratory.

Blood test for malignant neoplasms

Liver cancer and hepatitis are determined by identifying antigens to certain diseases. Hepatitis markers: A (HAV) – Anti-HAV-IgM, IgM class antibodies to virus A; B (HBV) – Anti-HBs antibodies to the HBs antigen of the B virus; C (HCV) – Anti-HCV-total antibodies to C virus antigens.

The tumor marker AFP becomes a marker for cancer. The disease is confirmed by a result of more than 10 IU. An increase in the indicator may indicate the presence of a malignant neoplasm in the organ itself, the presence of metastases, or embryonal cancer.

If there is a slight excess, you can suspect:

• cirrhosis;
• hepatitis;
• renal failure.

The presence of oncology is better indicated by a general clinical analysis in combination with biochemistry

Preparing for the test

Blood biochemistry is prescribed if it is necessary to check liver function. Proper preparation for donating blood will help you get the most accurate results. Two to three days before visiting the laboratory, you need to exclude fatty, fried foods, fast food, sweets, smoked foods, cocoa, coffee, and marinades from the menu.

You should stop drinking alcohol a week before the test. Ethyl affects not only the condition of hepatocytes, but also the blood clotting rate. On the morning of blood donation, the patient should not smoke. But it is better to give up nicotine 10–12 hours before visiting the laboratory.

7 days before the test, you must stop taking any medications, including vitamin complexes. If this is not possible, then you need to stop taking the pills at least on the morning of blood donation. A woman must be sure that she is not pregnant. Due to gestation, it is possible that the permissible norms may be exceeded. And this cannot be considered as a symptom of a pathological condition.

On the morning of donating blood, you should avoid doing morning exercises, since increased physical activity can affect blood counts. The donation of biomaterial is carried out in the morning, on an empty stomach. The last meal should take place the night before. Dinner should be light.

Blood is drawn from the ulnar vein. The procedure is painless, but may be accompanied by slight dizziness. The interpretation of the resulting analysis should be carried out by the attending doctor, since only a qualified specialist is able to compare all the data received and determine the presence or absence of pathology.

Which method is better and how to choose?

The best solution is a free consultation with a hepatologist, who will recommend exactly the examination that is most informative in your case. But you can independently determine the required examination method, and for this we recommend having complete information about each one.

When choosing, professional hepatologists are guided by specific criteria:

1. Information content of the method : what data about the liver can be obtained by this method, and what is the accuracy of this data. The more data there is, the more accurate and understandable the condition of the organ will be for the doctor, and therefore the effectiveness of treatment will be higher. Remember, for the liver, the most important evaluation parameter is the stage of fibrosis. It is very good if the method additionally provides information about the degree of steatosis, the presence of inflammation and the condition of the blood vessels, whether the lesion is focal or diffuse, but the assessment of fibrosis comes first.
2. Reproducibility and availability of the method : how often the examination can be repeated. Methods that allow frequent repetition allow you to effectively monitor the progress of treatment and, if necessary, adjust it. It is important that the frequency of repetition of the study is influenced not only by medical indications and contraindications, but also by its price.
3. Contraindications and complications : for some methods there are contraindications and complications are possible.
4. Accuracy of the method : liver diseases may be accompanied by diseases that can affect the results of tests or examinations.
5. Ease of examination : how long the examination itself takes, how long you need to wait for its results, whether preparation is needed on the part of the patient, whether this examination is invasive (there is a need to pierce the skin) or not. Most tests and research methods are quite safe, but some require special preparation, diet, or even hospitalization.

You determine the degree of importance of each of them in your particular case yourself, or this is done by the attending hepatologist.

The newest method for assessing the condition of the liver, ultrasound examination with elastography, most fully meets all of these criteria.