Elevated liver enzymes are a warning sign of possible liver damage, irritation, or inflammation. The liver releases several substances when it is injured, and two of these substances are enzymes called alanine transaminase (ALT) and aspartate transaminase (AST) . Elevated liver enzymes may be temporary or a sign of a medical condition like hepatitis or liver disease. Some common causes of elevated liver enzymes include:

• Non-alcoholic fatty liver disease (NAFLD): This is probably the main reason for elevated liver enzymes in children in the U.S. today. Mild forms of this disease are very common, and the more serious form that over many years can lead to cirrhosis (scarring) and liver failure is called non-alcoholic steatohepatitis (NASH) .

• Viral infections: Many viruses can temporarily increase liver enzyme levels. These include rhinovirus (common cold) or Epstein-Barr virus (EBV), the virus that causes mononucleosis (“Mono”) .

• Certain medications: Certain medications, such as cholesterol-lowering drugs (statins) and acetaminophen, can cause elevated liver enzymes.

• Drinking alcohol: Regular or heavy alcohol use can hurt the liver and increase liver enzymes.

• Heart failure: Heart failure can cause elevated liver enzymes.

• Hepatitis A, B, and C: These viral infections can cause elevated liver enzymes.

• Nonalcoholic fatty liver disease: This condition can cause elevated liver enzymes.

• Obesity: Obesity can cause elevated liver enzymes.

Other possible causes of elevated liver enzymes include toxic hepatitis (liver inflammation caused by drugs or toxins), autoimmune hepatitis (AIH), and hemochromatosis (a condition that runs in families) . If your blood test shows high levels of liver enzymes, talk with your healthcare provider. They will work to figure out the cause and may order more blood tests or imaging tests such as ultrasound, CT scan, or MRI. Treatment will depend on what’s causing the elevated liver enzymes.