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In the previous part of the article, biochemical tests assessing the function of the liver were discussed. This text introduces the role of more specialized laboratory tests in differentiating the basis of diseases of this organ.
Hepatitis A, B and C.
Infectious agents are, in addition to the toxic effects of drugs or alcohol, a significant threat to the liver. Among them, viruses that cause hepatitis A, B and C (viruses: HAV, HBV, HCV, respectively) deserve special attention.
Virus type It is spread both through the digestive tract and through contact with the secretions of the sick person. Usually, infection with it is asymptomatic and does not go into the chronic phase, and its occurrence, usually in the form of a mild infection in childhood, gives immunity to this type of virus.
Types B On the other hand, viruses and C viruses are transmitted only through the bloodstream and through secretions and excretions of the body, and the infection with them is acute or chronic, and can lead to cirrhosis and liver cancer. In the case of infection with hepatitis viruses, laboratory tests show the changes in biochemical parameters described in the previous part of the article (mainly multiple increases in ALT activity), but it is also necessary to perform specific immunochemical and molecular tests.
The first step in the diagnosis of viral infections is blood serology tests to detect viral fragments (antigens, Ag) or antibodies (Ab) against viral particles produced by the patient’s body. If the result is positive, it is necessary to confirm the infection by checking the genetic material of the virus (depending on the type of virus – DNA or RNA) in the patient’s blood. For this purpose, molecular methods (using the PCR technique) are used, which also enable the selection of the optimal therapy and monitoring of its effectiveness. During the treatment of HBV infection, changes (mutations) in its genetic material may occur, resulting in resistance to the drugs used. The effectiveness of hepatitis C treatment is influenced by the type (genotype) of HCV, as well as by the presence of certain forms of the IL28B gene in the DNA of an infected person.
It should be noted that hepatitis often begins asymptomaticallyTherefore, laboratory screening tests should be performed periodically, especially in people at risk (including medical staff, dialysis patients, people who inject drugs) and in couples planning to have children.
Modern medicine has a powerful weapon in the fight against hepatitis A and B – vaccinations. They are recommended, among others people who are exposed to human blood or plan to travel to the areas of increased prevalence of hepatitis A (Sub-Saharan Africa, South Asia). Prior to administration of the vaccine, the level of immunity to infection should be checked by determining the appropriate antibodies in the patient’s serum. For hepatitis A, it is sufficient (not requiring vaccination) to detect the presence of anti-HAV antibodies, in the case of HBV, the amount of anti-HBs antibodies above 100mIU / ml is necessary.
Liver cancer
The development of primary liver cancer may be a serious consequence of hepatitis B and C. A screening test to detect this tumor is the determination of alpha-fetoprotein (AFP) in the patient’s serum. Confirmation of the diagnosis is the concentration of this marker higher than 500ng / ml, with lower values the diagnosis should be confirmed by imaging tests – tumor markers are not entirely specific, their level also increases moderately in non-neoplastic diseases (in the case of AFP – e.g. in cirrhosis of the liver and chronic hepatitis). ).
Autoimmune liver disease
Liver dysfunction may also be autoimmune. Conditions such as autoimmune hepatitis (AIH type 1, 2 and 3), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are associated with autoantibodies (autoAbs) in the patient’s blood that attack different structures of the liver and ducts biliary tract, which can lead to fibrosis and cirrhosis, and even liver cancer.
Detection of disease-specific autoantibodies (presence, titer and type) enables early diagnosis, which improves the prognosis. However, it should be taken into account that the amount of autoAbs (expressed as a titer) varies throughout the course of the disease – it may be undetectable at some stages, and therefore a repeat test may be necessary. Moreover, autoAbs may be present in some healthy people, hence the interpretation of test results should be done by a specialist.
Genetic liver disease
Livers are also affected by genetic diseases. These include hereditary haemochromatosis, which consists in excessive absorption of iron, which is deposited in the tissues of organs such as the liver, heart or pancreas, causing damage. The early symptoms of the disease include:
- fatigue,
- arthralgia,
- gray discoloration of the skin.
The patient’s blood shows an increase in iron levels and an increase in transferrin saturation (TIBC test) and a higher concentration of ferritin. The detection of two mutations in the HEF gene also supports the diagnosis of the disease. Correct diagnosis, confirmed by genetic testing, determines the appropriate treatment and avoiding the dangerous consequences – cirrhosis of the liver, cardiomyopathy with arrhythmia and diabetes. Genetic diagnosis is also necessary to detect Gilbert’s syndrome. Mutations in the gene of one of the liver enzymes cause disturbances in bilirubin metabolism. Free bilirubin increases in the blood, and jaundice may appear periodically. The disease is not dangerous, but genetic testing for it is recommended due to the need to differentiate it from serious liver diseases.
Summarizing the above, it can be noted that laboratory tests allow for quick and accurate diagnosis of liver diseases, enabling their effective prevention and treatment.
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