Alanine aminotransferase (ALT) is a liver enzyme. It is produced in the cells of the liver as part of the liver’s normal function, and normally is not found in the bloodstream in high concentrations. When liver cells are damaged or killed, however, they can leak ALT into the blood and produce higher amounts, which can then be detected in a diagnostic blood test.
Prognosis
Elevated ALT is always considered a sign of some type and degree of liver damage or disorder. Other liver enzymes can be elevated as a result of injury or illness to other organs, and the liver’s response to the imbalances that result, but elevated ALT is a specific indicator of liver disease and/or liver damage that is considered very reliable. However, it does not indicate what type of liver disorder is present, nor the underlying cause.
Causes
There are many factors that can cause liver damage or liver diseases. These include alcohol abuse, obesity, diabetes, infectious diseases such as hepatitis, infectious mononucleosis, and herpes simplex, and other causes. Liver damage ranging from relatively mild and benign conditions such as fatty liver disease or liver hemangioma to very serious conditions such as cirrhosis of the liver or liver cancer can produce elevated levels of ALT.
As a result, further diagnostic efforts are usually required when the blood test reveals elevated ALT. This might include the use of medical diagnostic imaging (such as an ultrasound or magnetic resonance imaging), a biopsy, tests to rule out hepatitis, and assessment of lifestyle factors such as diet, exercise, and alcohol consumption.
Medications
In addition to liver diseases, some medications can cause elevated ALT. These include Tylenol, some antibiotics, cholesterol-
Pets
Elevated ALT can also sometimes be detected in dogs and cats. As in humans, a blood test is used to detect the elevated enzymes. Veterinarians normally test for a number of different enzymes at once, and as in humans, elevated ALT levels in animals can indicate any number of liver and related conditions, some serious, others not indicating a need for treatment.
When elevated ALT levels are detected, further diagnostic procedures are usually in order to determine what is causing it and whether changes to diet, exercise, medications, and so on are necessary or desirable.
In short, almost everything that is true about elevated ALT in humans is also true of the same condition in pets, except that normally neither cats nor dogs engage in excessive consumption of alcohol, so most of the time that problem can be ruled out.
Treatment
There is no treatment recommended for elevated ALT in itself. However, depending on the condition underlying the diagnostic result, treatment may be recommended including reduction or elimination of alcohol, dietary changes to increase fiber consumption and reduce fat intake, increased exercise, weight loss, changes in medication prescribed for other conditions, and further monitoring.
Additional tests may be needed to determine the presence or absence of hepatitis and other infectious diseases, fatty liver, cirrhosis of the liver, and liver cancer, as well as diabetes, alcoholism, and obesity and its complications.
Although the presence of elevated ALT is not necessarily indicative of a serious condition, the liver is such an important organ vital to bodily functioning on many levels that any sign of damage to or disorders of the liver is always cause for concern.