Elevated AST in the blood: what does this mean?
Many of us are sometimes skeptical about laboratory tests that are prescribed by physicians. Often this is the fault of our psychology: «the doctor said nothing, the diagnosis was not set, and subscribed to a lot of areas.» Our skepticism often, alas, has no ground, because laboratory studies (e.g., biochemical analysis of blood) can help to detect many diseases. Take, for example, such indicator of biochemical analysis of blood AST. What it means, what the acronym stands for, and what does this analysis?
In human blood there are hundreds and thousands of dissolved compounds. Many of them exist for a very short time and disappear, others enter the blood accidentally, and others are required to be present constantly. An important group of indicators of the body are enzymes (enzymes). Enzymes are substances that are able thousands of times to speed up (or slow down, which happens much less) the rate of chemical reactions in the human body.
Why do you need AST?
Interestingly, the enzymes in the reaction are not consumed, so the number of reagents they are not included and are the biological catalysts. Among such important for medicine belongs of enzymes AST, or aspartate aminotransferase. This is a complicated name, but it can be divided into parts: aspartate-amino-transferase. This means that the enzyme transfers the nitrogen residue on the substrate, transforming it into aspartate. This reaction is very important for the body, because the formation of urea. Thus, the AST enzyme involved in the catabolism of protein in the body.
These processes of intracellular and in the blood AST is contained in residual amounts because it hits the bloodstream only in the destruction of cells. Because even in a healthy organism every second there is a disintegration of hundreds of thousands of cells, AST is present in the blood. Its normal concentration is expressed in specific units per liter and has a «gender differences»:
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- norm AST for women is 0 to 31 units/l;
- the norm of AST for male is from 0 to 41 units/l.
What are the reasons for this difference in values? Do not think that the enzyme AST is evenly distributed on all cells. In human body highest concentration of this enzyme is in the muscle of the heart and inside the liver cells. And men weight liver and heart more than women. Now it becomes clear to us that if something happens with the heart tissue or liver (massive disintegration of cells), aspartate aminotransferase leaves the cells and is in the bloodstream. Therefore, the increase in ALT levels in the blood almost always is a signal of necrosis of cardiomyocytes and hepatocytes.
The reasons for the increase in the concentration of the enzyme AST in the blood
Elevated AST in the blood may be in the following diseases and conditions:
- acute myocardial infarction;
- viral, toxic, alcoholic hepatitis;
- cirrhosis of the liver;
- the defeat of the intrahepatic bile ducts and cholangitis.
Most often the study of the cytolysis (cell death) is prescribed in conjunction with other enzyme – ALT. Characteristically, if AST exceeds ALT readings, more likely «cardiac» cause, and if on the contrary – most likely the fault lies with the liver.
AST and jaundice
Also helps the study of this pair of enzymes (AST-ALT) in the differential diagnosis of jaundice. For example, we know that the child immediately after birth, sometimes there is an increased level of bilirubin at the normal reasons. This condition is called physiological jaundice of the newborn. To distinguish it from the parenchymatous (hepatic) jaundice, it is necessary to examine the blood for these enzymes. Their normal values are low, and if there is cytolysis and necrosis of hepatocytes (for example, congenital anomalies of the bile ducts), it will develop obstructive jaundice, and the values are high.
In the same case, if the jaundice is caused by massive breakdown of red blood cells and hemolysis occurs, these enzymes will not be increased, because in the blood cells and their activity is missing. As the red blood cells are intended for the transport of oxygen and the sequestration of carbon dioxide, each red blood cell is a unique and highly specialized «transport system». Therefore, the study of enzymes is a very important element of the diagnostic search, and it can not be neglected.