Transaminases are proteins that function as biological catalysts, facilitating chemical reactions within the body’s cells. These enzymes are part of metabolism, the process of converting food into energy and building blocks for the body. Specifically, they are involved in the production of amino acids, the molecules that link together to form proteins.
The Function of Transaminases
Transaminases, also known as aminotransferases, have a specific biochemical job: they catalyze the transfer of an amino group from an amino acid to an alpha-keto acid. This reaction allows the body to synthesize non-essential amino acids—those the body can make on its own. This process is part of protein metabolism and helps produce energy when blood sugar is low.
Two of the most well-known transaminases in medicine are Alanine Transaminase (ALT) and Aspartate Transaminase (AST). While both are involved in these amino acid exchange reactions, their primary locations within the body differ. ALT is found in high concentrations within the liver, making it a relatively specific indicator of liver cell health. AST is also present in the liver but is found in significant amounts in other tissues, including the heart, skeletal muscles, kidneys, and brain.
How Transaminase Levels Are Measured
The concentration of transaminases in the bloodstream is measured through a simple blood test. This test is frequently included in routine health screenings, such as a Comprehensive Metabolic Panel (CMP) or a Liver Function Test (LFT). A blood sample is analyzed in a laboratory to determine the activity of these enzymes, with results reported in units per liter (U/L).
The presence of these intracellular enzymes in the blood provides insight into cellular health. Under normal circumstances, ALT and AST reside inside organ cells and are present in the blood at low levels. When cells are damaged, their membranes can rupture, releasing their contents into the bloodstream. An increase in the measured levels of transaminases therefore signals that cellular injury or inflammation is occurring somewhere in the body.
Causes of Elevated Transaminase Levels
A variety of conditions, not all related to the liver, can cause transaminase levels to rise. Common causes include:
- Non-alcoholic fatty liver disease (NAFLD), a condition where excess fat accumulates in liver cells.
- Alcoholic liver disease, resulting from excessive alcohol consumption.
- Viral infections like hepatitis A, B, and C, which can cause significant inflammation and cellular damage.
- Certain medications, most notably acetaminophen when taken in large doses, which can also induce liver injury.
Other factors can lead to elevated transaminases, particularly AST. Because AST is also found in muscle tissue, strenuous physical exercise or a significant muscle injury can cause its release into the blood, raising levels temporarily. Other, less common causes for elevated enzymes include celiac disease, an autoimmune disorder triggered by gluten, and hemolysis, where red blood cells are destroyed at an accelerated rate. The specific pattern of elevation, such as the ratio of AST to ALT, can provide doctors with clues about the underlying issue.
Addressing Abnormal Transaminase Levels
Finding out you have elevated transaminase levels can be concerning, but the focus is not on lowering the enzymes themselves. The goal is to identify and manage the underlying condition that is causing the cellular damage and enzyme release. A healthcare provider will conduct a thorough evaluation, including a medical history, physical exam, and potentially further diagnostic tests.
Treatment is tailored directly to the diagnosed cause. For instance, if non-alcoholic fatty liver disease is the reason for the high levels, management involves lifestyle changes such as a modified diet and increased physical activity. If a particular medication is identified as the source, a doctor may adjust the dosage or switch to an alternative drug. In cases of viral hepatitis, specific antiviral medications may be prescribed. All management strategies should be guided by a healthcare professional.