Alanine aminotransferase (ALT) in the blood

Alanine aminotransferase (ALT) in the blood is a specific enzyme that shows how stable the state of the tissues of various human organs.

Alanine aminotransferase is generally a standard deviation, but alanine itself is an important enzyme found in large amounts in skeletal muscle, liver, heart and kidneys. This substance is actively involved in the metabolism and synthesis of various amino acids. ALT can enter the blood only in case of tissue damage, in a healthy state of the tissues of the internal organs, ALT is practically not present, and if it is observed, then in small quantities. Alanine in the tissues is also an amino acid that quickly converts to glucose, which gives energy to both the central nervous system and the brain. Strengthening the immune system, active participation in the production of lymphocytes, control of the metabolism of sugars and acids - all these are the functions that alanine performs.

The standards in which alanine aminotransferase must fit in the blood are:

Reference values (norm) of serum ALT activity - 7-40 IU / l.

• In men, no more than 40-41 units / l;
• In women - no more than 30-31 units / l.

In analytical studies on this enzyme, high accuracy is necessary, and it is directly related to the intake of certain drugs that may distort the analytical picture. Therefore, before checking the level of ALT, you should consult with your doctor, who will either temporarily cancel medication, or will take into account deviations in the results of the analysis associated with drug therapy. In addition, ALT in the blood depends on the age, for example, in babies just born, the level of ALT does not exceed 17 units. Then the amount of ALT gradually increases, this is due to the launch of all protective mechanisms in the body. Also for analytical studies depends on the ambient temperature.

[1], [2], [3]

Causes of increased ALT in the blood

Alanine aminotransferase is increased in such diseases as: 

• hepatitis, including viral; 
• toxic effects of alcohol, including cirrhosis ; 
• oncoprocess in the liver ; 
• drug intoxication; 
• heart disease, including failure; 
• myocarditis, heart attacks ; 
• shock conditions with burns and various serious injuries; 
• necrotic lesions of the skeletal muscles.

Also, alanine aminotransferase in the blood is usually elevated in all pregnant women. However, an excessive amount of ALT should alert the attending physician, since such an indicator may indicate a serious pathology of internal organs, especially the liver.

Increasing the activity of aminotransferases (AST and ALT) is 1.5-5 times compared with the upper limit of the norm is considered as moderate hyperfermentemia, 6-10 times as moderate hyperfermentemia, more than 10 times as high. The degree of increase in the activity of aminotransferases indicates the severity of the cytolytic syndrome, but does not directly indicate the depth of violations of the actual function of the organ.

In myocardial infarction, an increase in the activity of ALT in the serum is detected in 50-70% of cases, more often with extensive necrosis of the heart muscle. The greatest increase in ALT activity is detected in the acute phase - an average of 130-150% of the norm, which is noticeably inferior to that of AST - an average of 450-500% of the norm.

In diseases of the liver, ALT activity changes first and most significantly in comparison with AST. In acute hepatitis, regardless of its etiology, the activity of aminotransferases increases in all patients. The activity of ALT contained in the cytoplasm is particularly altered due to its rapid release from the cell and admission to the bloodstream, therefore, the determination of ALT activity is a more sensitive test for the early diagnosis of acute hepatitis than AST. The half-life of ALT is approximately 50 hours. AST is located predominantly in the mitochondria, its half-life is 20 hours, so its activity increases with more severe damage to the hepatocyte. The activity of ALT and AST increases 10-15 days before the appearance of jaundice with hepatitis A, and for many weeks with hepatitis B (the activity of these enzymes increases simultaneously, but ALT increases it to a much greater extent). With a typical course of viral hepatitis, ALT activity reaches a maximum at the 2-3rd week of the disease. With its favorable course, ALT activity normalizes in 30-40 days, AST - in 25-35 days. Repeated or progressive increase in the activity of aminotransferases indicates a new necrosis or recurrence of the disease. Lengthening the period of increased activity of aminotransferases is often an unfavorable sign, since it may indicate a transition of an acute process to a chronic one.

In the acute period of viral hepatitis in all forms, except for severe, the de Rytis coefficient ranges from 0.55 to 0.65, with a severe course this ratio averages 0.83, which reflects a more significant increase in AST activity. In the differential diagnostic relation, it is of some importance that, in alcoholic lesions of the liver, as opposed to viral lesions, the preferential increase in AST activity (de Ritis coefficient is more than 2) is characteristic.

For chronic hepatitis is characterized by moderate and moderate hyperfermentemia.

In latent forms of cirrhosis of the liver, an increase in the activity of enzymes is usually not observed. With active forms, a persistent, albeit a slight increase in the activity of aminotransferases is detected in 74-77% of cases.

Bilirubin-aminotransferase dissociation, that is, cases of severe hyperbilirubinemia (mainly due to direct bilirubin) and low activity of aminotransferases, deserves attention. This dissociation is observed in obstructive jaundice with stable biliary hypertension, acute hepatic failure. The activity of AST and ALT, as well as alkaline phosphatase increases with the resolution of chronic heart failure (the peak is usually 3-4 days).

An increase in the activity of ALT and AST can also be detected in practically healthy carriers of the hepatitis B surface antigen, which indicates the presence of apparently asymptomatic active processes in the liver.

[4], [5], [6], [7], [8]

Causes of ALT Reduction

Alanine aminotransferase can be below normal for very serious pathologies such as necrotic liver atrophy. Release, release of ALT into the bloodstream is possible only in case of defeat of hepatocytes, their cell membranes. In addition, the elemental deficiency of vitamin B6 can also affect the reduction of ALT levels.

Alanine aminotransferase in the blood is usually determined together with AST - aspartate aminotransferase, both of these indicators are important for assessing the condition of many internal organs.

[9], [10]