Blood test for liver tests: preparation, how to take, what shows

To assess liver function, special studies are conducted – liver tests. Let's consider the features of this analysis: indications, method of implementation, decoding of results.

The liver is the largest gland in the human body. It occupies the upper right section of the abdominal cavity, located under the diaphragm. All vital biochemical reactions occur in it, the disruption of which causes a number of negative consequences for the entire body. The parenchymatous organ has increased regenerative and restorative abilities, but its complex structure and high loads make the liver vulnerable.

The main functions of the liver:

• Detoxification – neutralizes toxic compounds entering the blood from the environment (toxins, food and drinks, medications) and removes them from the body.
• Regulation of carbohydrate, lipid, protein, bilirubin and vitamin metabolism.
• Synthesis of hormones: sex, thyroid, adrenal.
• Synthesis of bile and enzymes involved in the process of digestion and breakdown of fats.
• Hematopoiesis and synthesis of plasma factors of the blood coagulation system.
• Deposit (storage) and distribution of glucose and glycogen (energy substrates).
• Synthesis of immunoglobulins, antibodies and other proteins of the immune system.
• Blood storage and distribution according to the body's needs.

When changes occur in the functioning of an organ, its functions are disrupted and the general condition of the body worsens. To determine the cause of painful symptoms, patients are prescribed liver tests. This study is a set of tests that allow identifying various pathologies at early stages and conducting an objective assessment of the basic functions of the liver.

What is the name of the liver function test?

The liver is a kind of laboratory of the body, in which many chemical reactions occur every minute. Its work depends on the substances entering the body. Conducting a special set of laboratory studies allows you to get detailed information about the condition of the organ and the digestive tract.

The functional characteristics of the liver are determined through various procedures. The analysis of liver function tests is called screening and is assessed by the following indicators:

• Bilirubin.
• ALT (alanine aminotransferase).
• AST (aspartate aminotransferase).
• GTT (gamma-glutamyl transferase).
• ALP (alkaline phosphatase).
• Total protein (especially albumin is examined).

During the study, all of the above indicators or certain ones can be determined. The cost of laboratory diagnostics depends on the number of tests. For a comprehensive assessment of the liver condition, three main tests are mandatory:

• Comprehensive biochemical blood test.
• Coagulogram.
• General urine analysis.

The first analysis reveals pathological processes, determines their causes and provides information on the removal of bilirubin from the body, the creation of protein, albumin and other substances. The coagulogram determines disorders in the coagulation system to reduce the risk of increased bleeding. General urine analysis allows you to assess the general condition of the body, liver and kidneys.

Indications for the procedure

The danger of liver diseases is that they have a latent course, progress quickly and can cause death. That is why it is necessary to consult a doctor and undergo laboratory diagnostics if you have the following symptoms:

• Sudden weight loss without apparent reason.
• Frequent attacks of nausea and vomiting.
• Increased weakness.
• Rapid fatigue.
• Swelling of the abdomen, lower limbs and skin around the eyes.
• Heaviness and pain in the right hypochondrium.
• Diarrhea or discolored stools.
• Darkening of urine.
• Yellowish tint of the sclera and skin.
• Flatulence over a long period of time.

In addition to the above symptoms, indications for conducting a liver function test include suspicions of the following pathologies:

• Chronic liver diseases.
• Abuse of alcohol over a long period of time.
• Transfusion of blood and its components.
• Cirrhosis.
• Diabetes mellitus.
• Disorders of the endocrine system.
• Hepatitis: viral, drug-induced, autoimmune, toxic, allergic.
• Liver changes on ultrasound.
• Low ALT, AST levels.
• High levels of iron, gamma globulin.
• Decreased levels of thyroid-stimulating hormone, ceruloplasmin.
• Hormonal imbalances.
• Monitoring the side effects of drug therapy, especially antibacterial treatment.
• Evaluation of the effectiveness of the treatment.
• Preparation for surgery for any reason.
• Planning pregnancy.

If the test results show elevated levels of ALT and AST, this indicates damage to organ cells. The albumin level shows the efficiency of protein synthesis. Bilirubin shows how well the liver performs its detoxification function. As an additional examination, a thymol test may be prescribed to assess protein-synthetic function.

It should be taken into account that changes in liver function tests do not always indicate liver damage. For a comprehensive assessment of the test results, anamnesis is collected, the presence of painful symptoms is taken into account, a visual examination of the patient and a number of diagnostic tests are also necessary.

Preparation

In order for the liver function test to be as reliable as possible, you should prepare for it properly.

24 hours before the examination it is necessary:

• Avoid excessive physical activity.
• Eliminate fatty foods and alcohol from your diet.
• Reduce stressful situations to a minimum.
• Quit smoking.
• Do not drink strong tea or coffee.
• Take only medications prescribed by your doctor.
• If you have liver diseases, perform a tubage (cleansing of the gallbladder).

Antibiotics, antidepressants, hormonal oral contraceptives, chemotherapy drugs, barbiturate medications, as well as Aspirin, Paracetamol, and Phenytoin have a particular impact on the falseness of test results.

Technique of implementation

Liver function tests are indicated if liver disease is suspected, as well as in the presence of pathological symptoms: yellowing of the skin, pain in the abdomen and right hypochondrium, nausea, vomiting. The study is aimed at identifying:

• Inflammatory processes.
• Stagnation of bile.
• Liver duct lesions.
• Viral diseases and a number of other problems.

The technique of conducting liver tests involves monitoring any changes in the liver. The main method consists of taking venous blood. In this case, special attention is paid to preparation for the analysis. The patient should adhere to a certain gentle regimen, since the organ reacts to any changes in the body.

The analysis is carried out on an empty stomach. Two or three days before the test, you should avoid fatty and fried foods and alcoholic beverages. Particular attention should be paid to medications, since taking some medications leads to false test results.

How to take liver function tests?

The analysis is taken in the procedure room at the clinic or in a specialized laboratory. As a rule, the study is carried out on a doctor's referral. Before taking liver tests, the patient should limit physical activity, refuse alcohol and unhealthy food.

You should also stop taking medications 7-10 days before the examination. If this is not possible for medical reasons, you should inform your doctor about what medications and in what dosage were taken.

The test is performed on an empty stomach, you can drink only a couple of sips of water. At least 8-12 hours should pass since the last meal. Also, if necessary, a tubage is performed 5-7 days before the test.

How is a liver function test performed?

Blood sampling for liver function tests is performed from the cubital vein in a standard way. This study is part of a biochemical blood test. To reduce the risk of false results, there are certain requirements for the blood sample:

• For analysis, 5 ml of venous blood is collected.
• The tourniquet is applied for 1-2 minutes before blood sampling. This is necessary to avoid falsely high albumin values.
• The biological fluid is stored and transported in a dark container, since bilirubin is destroyed under the influence of light.

Immediately after the analysis, the patient is asked to sit for a while to prevent dizziness and fainting. Complications from taking a sample are rare, but may manifest themselves with the following symptoms: prolonged venous bleeding, hemorrhage under the skin at the site of the vein puncture, infection of the vein with the development of phlebitis. The results of the analysis are ready within 1-5 days. Based on their data, the doctor makes a further diagnostic plan.

Interpretation of liver function test results

Liver function screening should only be performed by a qualified physician.

Key research indicators:

Indicators	Women	Men
Bilirubin, µmol/l:
General	8.5 - 20.5	8.5 - 20.5
Direct	Up to 15.4	Up to 15.4
Indirect	Up to 4.6	Up to 4.6
Total protein, g/l	60 - 80	60 - 80
Albumin, %	40-60	40-60
AST, U/l	Up to 31	Up to 47
ALT, U/L	Up to 31	Up to 37
GGTP, U/L	Up to 32	Up to 49

Correct interpretation of the test results allows you to assess the nature of the organ's dysfunction, its detoxifying capabilities, and a number of other functions. Liver tests also provide an opportunity to analyze metabolic processes and the body's condition after prolonged drug therapy.

If the indicators change significantly above or below the norm, a repeat study is conducted. This is necessary to exclude errors during laboratory diagnostics or violation of the rules for preparing samples.

What does a liver function blood test show?

Liver function tests are a comprehensive laboratory screening. They can be used to detect liver or biliary tract diseases at their early stages. The study is aimed at determining the concentration of such substances:

• Aspartate aminotransferase.
• Alanine aminotransferase.
• Alkaline phosphatase.
• Gamma-glutamyl transpeptidase.
• Bilirubin: direct, indirect, total.
• Albumin (blood serum protein).
• Thymol test.

The results of biochemical diagnostics allow us to evaluate the functional characteristics of the organ, detoxification of harmful substances, characteristics of bile production and analyze metabolic processes in the body.

Normal values

When interpreting the results of a biochemical liver screening, the doctor is guided by normal test results. Deviations from the norm, both upward and downward, may indicate various pathological processes in the body.

Reference values of liver function tests for adults for the main indicators:

• AST – 0.1-0.45 mmol/hour/l.
• ALT – 0.1-0.68 mmol/hour/.
• GGTP – 0.6-3.96 mmol/hour/l.
• ALP – 1-3 mmol/hour/l).
• Total bilirubin: 8.6-20.5 μmol/l.
• Direct bilirubin – 2.57 µmol/l.
• Indirect bilirubin – 8.6 μmol/l.
• Total protein – 65-85 g/l.
• Albumin – 40-50 g/l.
• Globulin – 20-30 g/l.
• Fibrinogen – 2-4 g/l.

In an extended biochemical analysis to assess the functional capacity of the liver, the values of additional indicators are taken into account: glucose, urea, cholinesterase, lipase, cholesterol, prothrombin. The presence of deviations is a reason for further diagnostics of the organ's condition.

Normal liver function tests for women

Laboratory test results in women may vary depending on age and hormonal characteristics of the body. The value of some enzymes increases not only in liver pathologies, but also during pregnancy and lactation.

The norm for the main markers of liver tests for women:

Indicator	Meaning
AST	10-30 IU/L
ALT	7-40 IU/L
GGTP	8.8-22.0 IU/L In pregnant women up to 36 IU/L
ASF	Up to 31 years 39-92 IU/l Over 31 years 39-117 IU/L II trimester up to 190 IU/l III trimester up to 240 IU/L
Total bilirubin	3.4-17.1 µmol/l In pregnant women 3.4-21.6 μmol/l
Total protein	65-85 g/l
Albumen	35-50 g/l

The obtained results of the study are compared with the established norms. The analysis is decoded by a doctor, taking into account the presence of risk factors (alcohol abuse, medication, pregnancy, etc.). The error in the results also depends on the equipment used in the laboratory.

Normal liver function tests for men

To assess the condition of the liver, a laboratory screening is carried out for the main enzymes of the organ. Let's consider the normal values of liver test markers for men:

• ALT – 10-50 U/l. Elevated values may indicate viral hepatitis, alcohol intoxication, the presence of parasites in the liver, cirrhosis.
• AST – 15-21 U/l. Deviation in any direction indicates damage to hepatocytes. If the enzyme level is 20-50 times higher, then this is a sign of viral hepatitis, organ tissue necrosis.
• GGTP – 2-55 U/l. Elevated levels are typical for alcohol poisoning, hepatitis, cholestasis.
• Bilirubin - the norm for total is 6-20.5 μmol/l, direct is 3.4 μmol/l, indirect is 3.5-18.5 μmol/l. An increase in the enzyme level may be associated with helminthiasis, cirrhosis, viral hepatitis, and damage to the biliary tract.
• Alkaline phosphatase - the norm of this enzyme depends on the patient's age. In men under 30, ALP is 31-92 IU/l, after 30 years - 38-117 IU/l. Increased values are observed in case of metabolic disorders in the body, cirrhosis, cholestasis, alcohol intoxication. If ALP is reduced, this indicates thyroid diseases.

The results obtained are compared with established standards to identify any deviations.

Apparatus for conducting analysis

Liver function tests are performed on venous blood. Biological fluid is analyzed using automated methods. The main enzymes are determined using various devices. Liver markers are studied using flow cytofluorometry using laser semiconductors and hydrodynamic focusing. Colorimetric and kinetic analyzers can also be used.

In modern medical laboratories, the Cobas 6000 device (with 501 modules) is used to conduct liver function tests. The modular analytical system provides a wide range of biochemical and immunochemical tests.

The device is characterized by a flexible combination of various modules, which allows the creation of a consolidated serum work area, as well as specialized immunochemical and biochemical systems. The device detects all liver enzymes, substrates and specific proteins.

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Elevated liver function tests

Very often, the results of liver function tests indicate that the norms of various enzymes are exceeded. As a rule, the changes concern ALT and AST, so let's consider the main reasons for their increase:

• Incorrect preparation for the test: eating less than 10 hours before the test, alcohol abuse, fatty and fried foods, increased physical activity. False results occur when using certain groups of medications.
• Painful symptoms indicating liver damage: yellowing of the skin and mucous membranes, discomfort in the right hypochondrium, nausea and vomiting, itchy skin, increased fatigue.
• Previously suffered viral hepatitis, pancreatitis, peptic ulcer, cholecystitis, gastrointestinal diseases, damage to skeletal muscles or the cardiovascular system.

Elevated enzymes may indicate not only liver pathologies, but also other organs that contain this transaminase. Also, changes in indicators may be associated with early pregnancy.

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Liver function tests are low

Decreases in liver enzyme laboratory test values are much less common than elevated liver function tests.

Let's look at the main reasons for the decrease in screening results:

• Bilirubin - chronic renal failure, tuberculosis intoxication, acute leukemia, aplastic anemia, alimentary exhaustion, low red blood cell count.
• AST and ALT – vitamin B6 deficiency, general necrosis, liver rupture, cirrhosis. Below-normal values occur in oncological processes in the body, genitourinary infections, pancreatic disease, and in premature babies.
• Alkaline phosphatase – blood anemia, thyroid hormone deficiency, metal intoxication. Vitamin B12 deficiency, ascorbic acid, zinc, magnesium. Large blood transfusion, hypophosphatosia, placental insufficiency during pregnancy.
• Total protein and albumin – cirrhosis, atrophy, hepatitis, liver carcinoma. Long-term starvation and low-protein diets, gastrointestinal pathologies. Tissue injuries and burn injuries. Nephrotic syndrome, kidney diseases. Condition after heavy bleeding, blood poisoning, infectious diseases, hyperhydration. Congestive heart failure, hereditary pathologies, newborns.
• Gamma-glutamyl transferase - unbalanced diet, vitamin and mineral deficiency in the body, increased physical activity, vegetarianism. Low levels of GGTP are observed in patients undergoing treatment for alcoholism, when using hormonal contraceptives or ascorbic acid.
• Prothrombin time – deficiency of vitamins and minerals, cirrhosis, hepatitis, myeloleukemia, intake of hormonal drugs and anticoagulants.

Below normal values may be caused by failure to follow the rules of preparation for diagnostics or by violations during the analysis.

Liver function tests for hepatitis C

Anthroponotic viral liver disease has a characteristic symptom complex that allows one to suspect a pathological condition, begin its diagnosis and treatment. Liver tests are performed to detect hepatitis C. Particular attention is paid to the ALT and AST indicators, which most reliably indicate the degree of organ damage and the features of the disease progression.

Viral hepatitis C has a latent course, so it develops over a long period of time. Disturbances in enzyme activity do not appear immediately. As hepatocytes are destroyed, the results of liver tests change.

Laboratory diagnostics of hepatitis C is carried out using the de Ritis coefficient (the ratio of ALT and AST):

• If the indicator increases more than 1.3 times, this indicates liver damage.
• If the coefficient is below the norm, then there is a suspicion of cardiovascular diseases.
• If the disease becomes chronic, the indicators are consistently high.

Hepatitis C of the icteric form is characterized by a simultaneous increase in ALT, direct and total bilirubin. In some cases, the disease occurs without yellowing of the skin and mucous membranes, so hepatitis can only be suspected by an increase in the production of enzyme substances in the results of liver tests.

The final diagnosis of hepatitis C is made on the basis of screenings, instrumental studies, and the presence of symptoms characteristic of the disease. After recovery, all enzymes return to normal.

Liver function tests in cirrhosis

Expressed structural changes in liver tissues causing liver failure, increased pressure in the tributaries and portal vein of the organ - this is cirrhosis. The disease is characterized by a chronic course and rapid progression.

The main causes of cirrhosis are:

• Alcohol abuse.
• Viral hepatitis.
• Severe intoxication of the body.
• Autoimmune processes.
• Gallstones.
• Narrowing or blockage of ducts.
• Helminthiasis over a long period of time.
• Chronic heart failure.

The disease manifests itself with secondary symptoms that do not always cause concern. But as it progresses, the skin and sclera of the eyes begin to turn yellow, pain appears in the right side, nausea and vomiting attacks, and the vascular network expands.

Liver tests are one of the main methods of diagnosing cirrhosis. Let's consider the main screening indicators and their meaning in case of structural changes in the liver:

• ALT – the enzyme level is increased by 10 or more times, reaching 500-3000 IU/L.
• AST – elevated values indicate the process of destruction of hepatocytes.
• GGTP – increases several times. A consistently high level indicates an extremely serious condition of the organ and active destruction of its cells.
• ALP - elevated values indicate cytolysis of hepatocytes and obstructed bile flow.
• Bilirubin – an increase in the norm of two fractions over 20.5 μmol/l, incomplete binding of enzyme molecules.
• Albumin - a decrease in the norm indicates severe damage to hepatocytes.

If cirrhosis is suspected, the patient is prescribed a set of laboratory and instrumental diagnostic procedures that allow confirming or refuting the diagnosis. It is impossible to cure cirrhosis even in its early stages. Patients are prescribed lifelong maintenance therapy to eliminate painful symptoms.

How long does it take to do a liver function test?

A comprehensive blood test to determine the functional state of the liver and biliary tract is performed by taking venous blood. The duration of the study is from 1 to 5 days. If the diagnostics are carried out in a modern medical laboratory using the latest generation modular analytical systems, the results are ready the next day.

What to do if liver function tests are bad?

Only a doctor should decipher and study the analysis of liver function tests. The doctor compares the results obtained with the normal values, the general condition of the patient and the presence of painful symptoms.

In case of significant deviations of the analysis without a pronounced symptom complex, the patient is prescribed a repeat examination. False results may be associated with a violation of the rules of preparation for the analysis or laboratory errors.

If elevated enzymes are accompanied by signs of liver damage, additional studies are carried out to more accurately assess the condition of the organ. After a comprehensive diagnosis, treatment and corrective methods are selected.

Treatment for liver function tests

Elevated liver enzymes very often signal the body about heavy loads on the liver. Such test results can be caused by the accumulation of toxins in the organ, certain diseases of the liver or other internal organs. Markers are higher than normal when taking certain medications during diagnostics.

If bad tests are all related to inflammation or liver damage, then additional diagnostics are performed and treatment is prescribed. Therapy is aimed not only at normalizing the indicators, but also at eliminating the cause of the painful condition.

Most often, treatment for liver function tests consists of a gentle diet and taking hepatoprotectors. This group of drugs restores damaged liver cells, preventing their further destruction. To speed up recovery, the patient must give up alcohol and smoking, eating fatty foods, coffee and carbonated drinks. Particular attention is paid to the prevention of chronic diseases of the body that negatively affect the functioning of the liver.