One of the precise diagnostic techniques that allow to track pathological changes in the body and to suspect the development of certain diseases at an early stage is a biochemical blood test. This study is conducted to determine the status of all organs and systems, for which the quantitative indicators of many blood components are analyzed. One such indicator is the level of alanine aminotransferase (ALT). Consider what kind of substance it is, and what kind of abnormalities can be indicated by the elevated ALT value found in the analysis of venous blood.
What is ALT in a blood test?
Alanine aminotransferase is an endogenous enzyme belonging to the transferase group and a subgroup of aminotransferases. It is produced by liver cells - hepatocytes. ALT is found mainly in the liver, but some of this enzyme is also found in the kidneys, heart muscle, pancreas and skeletal muscle tissue. A small part of this enzyme is normally found in the blood (the index for women is up to 31 U / l).
The main function of alanine aminotransferase is associated with the exchange of amino acids. This substance acts as a catalyst in the transfer of certain molecules. When the energy metabolism is disturbed, the permeability of the cell membranes increases, which leads to the destruction of cells and the release of the enzyme into serum.
The causes of elevated blood ATL
If the biochemical analysis shows that ALT in the blood is elevated, the reason for this in most cases is liver damage. But also the concentration of this substance can increase due to pathologies of other organs. Let's consider, at what exactly illnesses and on how much ALT level can exceed norm:
- A 20 to 100-fold increase in ALT may indicate acute hepatitis due to viral or toxic damage. In acute viral hepatitis A, this increase is observed approximately two weeks before the appearance of jaundice, and after 3 weeks its normalization occurs. With viral hepatitis B and C, ALT can increase unpredictably, and then decrease to normal values. An increase in this indicator can also be observed with exacerbation of chronic hepatitis, but in this case, excess of the norm occurs 3 to 5 times.
- If ALT is increased 2 - 3 times, then it can talk about non-alcoholic fatty liver disease (steatosis). The pathology transition to the phase of steatohepatitis is accompanied by a significant increase in ALT level, as well as an increase in the high level of total and direct bilirubin.
- Fivefold increase in the amount of alanine aminotransferase in the blood is often found in liver cirrhosis, which is associated with an intensive process of replacement of hepatic cells with a connective tissue.
- Sometimes an increase in the level of this enzyme is detected with metastatic liver damage. In this case, the larger the lesion, the greater the concentration of ALT in the blood. However, with a primary tumor, for example, with hepatocellular carcinoma, the deviations from normal ATL are insignificant, which often complicates the diagnosis.
- The increase in ALT to 600 U / L followed by a sharp decrease is a characteristic sign of acute obstruction of the bile ducts.
A slight excess of the norm can be observed when:
- myocardial infarction;
- myocarditis;
- heart failure;
- acute pancreatitis ;
- shock state;
- alcoholic hepatitis;
- infectious mononucleosis;
- myositis;
- acute lymphoblastic leukemia;
- severe gestosis in pregnant women (II trimester), etc.
Also, the increase in ATL may be a consequence of taking such medications as:
- cholestatics;
- oral contraceptives;
- estrogens;
- a nicotinic acid;
- sulfonamides and others.