In this Article

• Introduction to liver blood test
• What are the aminotransferases?
• Normally, where are the aminotransferases?
• What are normal levels of AST and ALT?
• What do elevated AST and ALT mean?
• What liver diseases cause abnormal aminotransferase levels?
• What medications cause abnormal aminotransferase levels?
• What are less common causes of abnormal aminotransferase levels?
• How are healthy people evaluated for mild to moderate rises in aminotransferase levels?
• How about monitoring aminotransferase levels?
• What about other liver enzymes?
• Patient Discussions: Liver Blood Tests - Helped With Your Diagnosis
• Liver Blood Tests Index

What liver diseases cause abnormal aminotransferase levels?

The highest levels of AST and ALT are found with disorders that cause the death of numerous liver cells (extensive hepatic necrosis). This occurs in such conditions as:

• acute viral hepatitis A or B,
  
  
• pronounced liver damage inflicted by toxins as from an overdose of acetaminophen (brand-name Tylenol), and
  
  
• prolonged collapse of the circulatory system (shock) when the liver is deprived of fresh blood bringing oxygen and nutrients.

AST and ALT serum levels in these situations can range anywhere from ten times the upper limits of normal to thousands of units/liter.

Mild to moderate elevations of the liver enzymes are commonplace. They are often unexpectedly encountered on routine blood screening tests in otherwise healthy individuals. The AST and ALT levels in such cases are usually between twice the upper limits of normal and several hundred units/liter.

One of the most common cause of mild to moderate elevations of these liver enzymes is fatty liver. In the United States, the most frequent cause of fatty liver is alcohol abuse. Other causes of fatty liver include diabetes mellitus and obesity. Chronic hepatitis C is also becoming an important cause of mild to moderate liver enzyme elevations.

What medications cause abnormal aminotransferase levels?

A host of medications can cause abnormal liver enzymes levels.

Examples include:

Pain relief medications such as:

• aspirin,
  
  
• acetaminophen (Tylenol),
  
  
• ibuprofen (Advil, Motrin),
  
  
• naproxen (Naprosyn, Naprelan, Anaprox, Aleve),
  
  
• diclofenac (Voltaren, Cataflam, Voltaren-XR)), and
  
  
• phenylbutazone (Butazolidine)

Anti-seizure medications such as:

• phenytoin (Dilantin),
  
  
• valproic acid (Depakote, Depakote ER, Depakene, Depacon),
  
  
• carbamazepine (Tegretol, Tegretol XR, Equertro), and
  
  
• phenobarbital

Antibiotics such as:

• tetracyclines, [for example, tetracycline (Achromycin)]
  
  
• sulfonamides,
  
  
• isoniazid (INH) (Nydrazid, Laniazid)
  
  
• sulfamethoxazole (Gantanol),
  
  
• trimethoprim (Trimpex; Proloprim, Primsol)
  
  
• nitrofurantoin (Macrodantin; Furadantin; Macrobid),
  
  
• fluconazole (Diflucan ) and some other anti-fungals, etc.

Cholesterol lowering drugs such as:

• the statins:
  
  
  • lovastatin (Mevacor, Altocor),
    
    
  • pravastatin (Pravachol),
    
    
  • atorvastatin (Lipitor),
    
    
  • fluvastatin (Lescol),
    
    
  • rosuvastatin (Crestor),
    
    
  • simvastatin (Zocor), and
  
  
• niacin

Cardiovascular drugs such as:

• amiodarone (Cordarone),
  
  
• hydralazine (Apresoline)
  
  
• quinidine (Quinaglute, Quinidex), etc.

Other drugs

Anti-depressant drugs of the tricyclic type

With drug-induced liver enzyme abnormalities, the enzymes usually normalize weeks to months after stopping the medications.

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