Liver tests

Liver tests are the most popular laboratory blood test that gives a general idea of ​​the functioning of an internal organ. An objective assessment helps the doctor to determine the possible pathologies of this organ, based on complex biochemical parameters. Diagnostics is also aimed at monitoring the dynamics of possible undesirable changes due to therapy with a long course of treatment with pharmacological drugs that have a hepatotoxic effect. We are talking about classical chemotherapy during the treatment of oncological neoplasms, pulmonary tuberculosis, systemic pathology, the use of antibacterial agents and immunomodulators.

Standard Readings

A biochemical blood test is rarely done as a preventive measure. As a rule, it is prescribed for suspected liver dysfunction. A prophylactic test is performed as a control during long-term use of antibiotics or medications that are metabolized by liver enzymes. At the same time, increased results are a completely expected development of events.

In such a situation, the doctor considers a scheme to neutralize or at least reduce the toxic load on one of the most important detoxifying organs.

But sometimes a referral for a clinical trial is issued to a patient with characteristic symptoms that cannot be explained by other diseases. Classical signs include the appearance of icterus of the sclera and skin. Additionally, there may be complaints of heaviness in the right hypochondrium and even a pronounced pain syndrome, which may be accompanied by a bitter taste in the mouth, as well as nausea and fever.

In addition to the fact that a laboratory study is necessary to assess the dynamics of liver diseases, it is used to monitor the hepatobiliary system. We are talking about possible inflammation of the bile ducts, bile stasis, hepatitis of viral or toxic origin. Sometimes the study also helps to clarify the diagnosis of parasitic invasion.

Liver tests indicate the degree of damage to liver cells (hepatocytes), which make up approximately 70% of the total organ cell pool. Detected changes at an early stage allow you to make adjustments to the treatment program.

An important factor in liver problems is chronic alcoholism, in which the indicators will also differ from the reference ones. A detailed biochemical analysis demonstrates the severity of liver dysfunction, including toxic cirrhosis and alcoholic hepatosis.

Examination rules

Before passing the analysis, you must familiarize yourself with the rules of the preparatory stage. A study is scheduled for the first half of the day, in a state on an empty stomach. Approximately 10 hours should elapse before the examination in the laboratory since the last meal. You can drink only unsweetened drinks with added sugar, or still water. Such stringent measures are aimed at obtaining reliable results that are not distorted by the influence of external random factors.

There are a few more practical recommendations that should be followed to obtain a more accurate result:

• avoid physical exertion before delivery, up to the refusal of morning exercises;
• do not drink alcoholic beverages the night before;
• do not smoke in the morning before the appointed time.

The blood sampling itself is made from the cubital vein, and the indicators, as a rule, are determined on a modern automated biochemical analyzer.

Ignoring the above rules can lead to inflated results. In the best case, the patient will need a second examination, and in the worst case, they will be prescribed medications for non-existent diseases.

In addition to violations of the preparation rules, there are several other factors that can distort the results of the analysis:

• pregnancy;
• obesity;
• the action of certain pharmacological preparations;
• strong compression of the vein with a tourniquet;
• adherence to a vegetarian diet;
• insufficient physical activity in daily life.

The results of the analysis make it possible to assess the functional ability of the liver as a whole, as well as to identify possible stagnation of bile and damage to the cellular structure. The degree of damage and the sites involved in the inflammatory process affect the synthetic and biochemical processes in the liver.

Each pathology is characterized by a certain symptom complex, which can affect the parameters of several indicators at once.

What will the result say?

Deciphering the results of a functional study is carried out by a doctor based on the results of the examination. A biochemical blood test demonstrates the functional state of the liver and its detoxifying function. In the normal state, it removes metabolic products from the circulatory system and prevent poisoning.

The main parameters obtained from a biochemical blood test include:

• albumin content;
• prothrombin time;
• transaminases;
• gamma-glutamyl transpeptidase (GGTP);
• ALP (alkaline phosphatase);
• bilirubin.

Albumin is a blood protein synthesized by liver cells. Despite the importance of the level of total protein, it is important to pay attention to the change in the ratio of protein fractions.

An increase or decrease in the content of albumin may indicate that the patient suffers from disorders not only of the liver, but also of the kidneys. Usually this is a consequence of malnutrition, as well as the reasons for the decrease in albumin concentration are:

• cirrhosis;
• neoplasms of various etiologies;
• hepatitis;
• rheumatoid conditions;
• bowel disease.

Pregnancy, malnutrition, and oral contraceptives can affect albumin levels. An increase in protein content is possible with severe dehydration due to changes in blood viscosity.

The prothrombin time indicates the ability of the liver to synthesize blood coagulation factors. A decrease in this indicator occurs with liver failure.

When considering the level of transaminase, it should be borne in mind that it includes two indicators:

• alanine aminotransferase (ALT);
• aspartate aminotransferase (AST).

They indicate the presence of a pathological process that is localized in hepatocytes, brain cells and myocytes. As a rule, deviations from the reference range indicate the possibility of developing:

• infectious hepatitis;
• myocardial infarction;
• cirrhosis of the liver;
• metastases in the liver.

Non-standard values ​​will also tell about the consequences of chronic alcoholism and pancreatitis, the normal limits for AST are in the range from 7 to 40 IU / l, and for ALT – from 5 to 30 IU / l. If the numbers are significantly outside the normal range, then this is evidence of hepatitis of toxic or viral etiology.

Low levels of liver enzyme activity may indicate:

• about pregnancy;
• insufficient intake of vitamin B6;
• renal failure.

An important indicator is the change in the content of bilirubin, since it is the first to respond to functional disorders in the liver.

The level of direct or indirect bilirubin increases with hepatitis of any etiology, with obstruction of the bile ducts, taking hepatotoxic drugs, or congenital pathology associated with a violation of the outflow of bile. An increase in bilirubin may be a side effect of a low-calorie diet, or starvation.

The detected changes in the content of GGTP help to determine the onset of liver disease when other specific parameters remain within the normal range. An increase in the criterion indicates the development of hepatitis of toxic or infectious etiology, blockage of the bile ducts, and metastatic liver damage.

Other possible reasons for deviations include:

• alcoholic hepatitis;
• pathology of the pancreas;
• diabetes;
• diseases of the gastrointestinal tract;
• cardiac pathologies.

Another trigger for an increase in GGTP may be the use of contraceptives.

Elevated levels of alkaline phosphatase are the standard for newborns, as they grow older, they decrease and are determined in the range from 50 to 150 IU / l.

An increase in the level can signal the growth of bone tissue, the formation of metastases in the bone structure, obstruction of the bile ducts, as well as liver damage due to drug therapy.

Abnormally high activity of alkaline phosphatase in adult patients may indicate endocrine diseases, which are provoked by a change in the concentration of hormones produced by the corresponding glands. Decreased activity of alkaline phosphatase may be due to dysfunction of the thyroid gland.

Additional markers

Usually, with the results obtained, the patient is sent to the attending physician to prescribe the appropriate treatment.

Sometimes, to establish an accurate diagnosis, you will need to undergo a series of additional diagnostic procedures: ultrasound or computed tomography.

Also, an extended biochemical blood test may include coagulation tests that provide information on the ratio of protein fractions in thymol and sublimate samples. Their determination in blood serum is also used in the diagnosis of liver diseases. For their implementation, the patient’s blood serum is used and its interaction with special reagents (thymol in veronal buffer and mercury chloride with sodium carbonate) is evaluated. At its core, thymol and sublimate tests make it possible to assess the levels of serum albumin, a-, b-, g-globulins and lipoproteins. These indicators make it possible to judge liver pathologies, including those of an infectious, autoimmune and oncological nature.

The sublimate test is more typical for an acute process. In the first five days with acute hepatitis, the thymol test will be positive in 80% of cases, however, with obstructive jaundice, this parameter remains within the normal range, which is used in clinical practice for the differential diagnosis of jaundice.

The sublimate test is more specific for chronic processes, it allows for operational monitoring of hepatic functions.

With hepatitis and cirrhosis, the test will be positive, even in the initial stages of the course of the disease.

A positive test will be when the parenchyma is damaged, which is caused by an infectious or toxic agent. An important criterion is also deviations in the content of fibrinogen, which belongs to the category of special proteins circulating in the bloodstream and participating in the blood coagulation system.

Based on all these criteria, the doctor confirms the diagnosis or refutes his suspicions.

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