Transaminase

Involved in amino acid metabolism and glucose synthesis, transaminases may be indicators of liver damage.

What are they

Transaminases (also known as aminotransferases) are enzymes involved in amino acid metabolism and glucose synthesis.

It is a rather large group of molecules, but the type of reaction in which they are involved is always the same: the transfer of the amino portion (the one containing nitrogen) from an amino acid to an acid molecule (called alpha-keto acid) to transform it into another amino acid.

What changes is the amino acid from which the amino group is taken, specific for each enzyme; There are, for example, a cysteine transaminase, a glycine transaminase, a tyrosine transaminase (produced by the thyroid) and a leucine transaminase.

Among all, however, there are two most interesting transaminases from a clinical point of view: aspartate transaminase (AST, or aspartate aminotransferase) and alanine transaminase (ALT, or alanine aminotransferase).

The first, formerly also known by the acronym GOT (glutamate oxaloacetate transaminase), uses aspartate to produce glutamic acid; the second, formerly known as GPT (glutamate pyruvate transaminase), always produces glutamic acid but using alanine as the starting amino acid.

The amino group acceptor keto acid is alpha-ketoglutarate (also called 2-oxoglutarate).

AST and ALT: the clinical significance

AST and ALT are particularly abundant in liver cells and any damage to the liver can lead to an increase in their blood; For this reason they are often analyzed to evaluate the functionality of this organ.

However, transaminases can also increase due to disorders that do not affect the liver or gallbladder.

In general, increases in AST may be associated with cirrhosis, liver tissue death, heart attack, excess iron (hemochromatosis), hepatitis, hepatic ischemia, liver tumors, taking liver-toxic medications, mononucleosis, muscle disease or trauma, pancreatitis, severe burns, heart surgery, seizures, and surgery.

Increases in ALT can instead be the sign of cirrhosis, death of liver tissue, hepatitis, hemochromatosis, fatty liver, hepatic ischemia, liver tumors, taking drugs toxic to the liver, mononucleosis or pancreatitis and other diseases and infections, acute or chronic, that affect the liver. Such pathologies can have particularly serious long-term effects and reactions not only on this organ but on the whole organism.

As for the liver specifically, by comparing the levels of AST and ALT it is also possible to understand what type of problem you are dealing with.

A comparable increase in both enzymes is typical of acute viral hepatitis, toxic or induced by different substances of alcohol. In the case of chronic hepatitis, cirrhosis and alcohol-associated hepatitis, blood levels of AST are higher than those of ALT.

Finally, gallbladder problems may also be associated with greater variations in AST than those in ALT, but typically cause more limited increases than other liver problems.

On the basis of the reports of clinical analyzes that certify the presence of similar problems, a general practitioner can decide what could be the best treatment to bring the reference values of his patients back to normal and restore health to organs and, in particular, to various tissues and liver cells.

The reference levels

In the absence of health problems, transaminase levels are roughly between:

Under normal conditions, the AST/ALT ratio is around 0.8. For women, however, attention should be paid to any variations associated with particular periods, such as pregnancy or menopause, as these fluctuations are not necessarily a sign of underlying liver problems.

Typically 10-20-fold increases in transaminases these concentrations are associated with liver damage; These high values can be associated with various pathological conditions. However, the reference levels may vary slightly depending on the testing laboratory where the test was carried out; Also for this reason, to correctly interpret the results of blood tests (carried out for the evaluation of transaminases, but not only) it is always good to rely on a doctor.

Moreover, since, as mentioned, the increase in transaminases can also depend on non-hepatic problems, the intervention of several specialists may be required to identify the necessary treatment and for the prevention of further changes in the levels of these liver enzymes.

Medical intervention always starts from any changes in nutrition, possibly suggesting the intake of food supplements (in case of food allergy to certain foods useful for the liver), and lifestyle. Only in this way can we hope to bring the parameters back to normal, so as to fully recover the patient’s liver function.

Transaminases and alcoholism

Alcohol is a toxic substance for the liver. The types of damage it can induce range from simple steatosis (or fatty liver), ie the accumulation of fats inside the organ, to cirrhosis, passing through alcoholic hepatitis and fibrosis, all diseases and conditions that reduce cell function and can bring with them signs and symptoms even serious.

The risk of developing diseases of this type depends on several factors, including age, sex, being smokers or not, genetic factors and the possible presence of obesity or chronic viral hepatitis, or a liver disease of another nature. If even one of these elements is present, it is good to pay some extra attention to the health of your liver.

Although there is a relationship between increased alcohol consumption and increased risk of developing liver disease, there is no minimum consumption threshold below which alcohol has been shown not to damage the liver; At the same time, there is no linear correlation between the increase in consumption levels and that of the severity of the disease developed in the liver.

In general, to deal with hepatic steatosis is a variable share between 60% and 90% of people who consume more than 60 grams of alcohol per day, corresponding to 5 alcoholic units. By continuing to consume alcohol less than 50% will develop fibrosis and between 10% and 20% will sooner or later find themselves struggling with liver cirrhosis and, possibly, its symptoms.

In case of steatohepatitis the risk of cirrhosis is even greater, especially if alcohol consumption is not stopped. Conversely, in the presence of a diagnosis of liver cirrhosis, abstention from alcohol consumption for at least 1 year and a half is associated with increased survival. A correlation has also been identified with the consumption, in parallel, of a quantity of water lower or higher than that recommended to maintain the health and well-being of the human body.

A blood sample aimed at checking transaminase levels is a useful tool in diagnosing liver disease associated with alcohol consumption. In particular, as mentioned, the suspicion that you may suffer from one of these disorders is concrete when the levels of aspartate amino transferase (GOT or AST) are higher than those of alanine aminotransferase (GPT or ALT).

However, it may happen that, even in the case of liver health problems related to alcoholism, the blood levels of transaminases highlighted by blood samples are not higher than normal. Similarly, the extent of the increase in transaminases does not depend on the severity of the liver problem. In general, however, in cases of alcohol-dependent liver damage, AST levels are 2 to 3 times higher than those of ALT.

To arrive at a correct diagnosis, however, it is necessary to exclude all other possible causes of liver health problems, such as hepatitis of viral or autoimmune origin and drug abuse. In some cases, a liver biopsy may also be necessary.

Transaminases and gallstones

In some cases, in addition to the concentration of transaminases, that of another marker in the circulatory stream, alkaline phosphatase, may also increase, and gallbladder stones may be present. In these situations, a decompression of the biliary tract is sufficient to bring the transaminase values within the norm, helping to resolve the alteration and the underlying disorder.

Transaminases and muscle damage

As already mentioned, another possible cause of high transaminases is damage to the muscles; Muscle structures can be damaged both in the presence of myopathy and due to very intense exercise. Not only that, trauma to the heart muscle (for example a myocardial infarction) and damage to the muscles caused by surgery can also lead to an increase in transaminases.

In all cases it is the natural process of muscle repair, which involves increased inflammation, to determine the alterations of amino transferase detectable with blood tests.

As for exercise, high transaminases are more often caused by anaerobic activities (such as weight lifting, but also very heavy physical labor) rather than aerobic ones (such as running).

A special case is that of marathon runners: if the muscle tissues of marathon runners undergo rhabdomyolysis, there may be a significant increase in transaminases, in particular AST and the ratio of AST / ALT, which can exceed the value of 3. However, AST levels tend to decrease rapidly over a few days, during which the AST/ALT ratio decreases to 1.

In general, values can remain elevated for up to 1 week. In the event that the trigger is exercise that requires intense expenditure of energy, further high-intensity workouts can lead to a new increase in transaminases.

In this circumstance, high transaminases may not be associated with any other particular symptom, but they generally correlate with the increase of two markers of muscle damage: creatine kinase and lactate dehydrogenase.

If the values found in laboratory tests exceed 2 times the maximum limit considered normal, it is good to consider the hypothesis that at the base of the increase there is not only physical activity, but also a liver health problem.

In general, moderate physical activity can help counteract the increase in ALT and AST in case of liver problems. On the other hand, it is not advisable to practice intense physical exercise, which could worsen the situation and frustrate the processes of treatment and the therapy eventually undertaken.

If in doubt, before undergoing any physical activity, it is advisable to contact your doctor or consult a sports medicine specialist, so as to carry out all routine examinations and monitor the correct functioning under stress of all organs, including the liver.