Alanine aminotransferase (ALT) is an enzyme found in the liver and in smaller quantities in other tissues including kidneys, heart and muscles. When liver cells are damaged, ALT is released and blood levels increase.
ALT may be done to assess liver function in the following conditions:
- Known or possible infection with hepatitis viruses, Epstein Barr Virus or Cytomegalovirus
- Family history of liver disease
- Intake of hepatotoxic drugs
- Evaluation in alcoholism
- Monitoring therapy in patients with liver disease
- Evaluating patients with symptoms suggestive of liver disease such as
Additional information:
- In normal males, the levels are significantly higher than in normal females
- Independently related to the body mass index of the person
- More sensitive for detecting hepatocellular damage than cholestasis
- ALT values are compared to levels of other liver enzymes like alkaline phosphatase and aspartate aminotransferase to determine the type of liver disease present
- ALT test is more specific than the aspartate aminotransferase (AST) in detecting hepatocellular injury
- In viral hepatitis, the ALT is usually more elevated than the AST (the reverse is typical in alcoholic hepatitis)
Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.
| Conv. units (U/L) | SI units (µKat/L) |
---|
<1 yr | 6-45 | 0.10-0.77 |
>1 yr Male | 10-50 | 0.17-0.85 |
>1 yr Female | 7-35 | 0.12-0.59 |
Note: Obesity often increases ALT levels.
Very high levels of ALT may occur in the following conditions:
- Acute liver damage (e.g. acute viral hepatitis)
- Hepatotoxic drugs
- Lead poisoning
- Necrosis of a large tumor
- Shock
Mild to moderately high ALT levels may be seen in the following conditions:
Slight increases in ALT levels may be seen in the following conditions:
Chronically elevated ALT levels maybe seen in the following conditions:
Drugs and substances that may cause an increase in ALT levels include:
- Drugs that cause cholestasis
- Amitriptyline
- Anabolic steroids
- Androgens
- Atorvastatin
- Benzodiazepines
- Carbamazepine
- Chlorothiazide
- Chlorpropamide
- Dapsone
- Digitalis
- Erythromycin
- Estrogen
- Ethionamide
- Glipizide
- Gold salts
- Imipramine
- Isoniazid
- Lovastatin
- Mercaptopurine
- Nitrofurans
- Oral contraceptives
- Penicillins
- Phenothiazines
- Phenytoin
- Pravastatin
- Progesterone
- Propoxyphene
- Simvastatin
- Sulfonamides
- Tamoxifen
- Tolbutamide
- Drugs and substances that cause hepatocellular damage
- Acetaminophen (toxic)
- Acetylsalicylic acid
- Allopurinol
- Amiodarone
- Anabolic steroids
- Anticonvulsants
- Asparaginase
- Aspirin
- Azithromycin
- Benzodiazepines
- Bromocriptine
- Captopril
- Cephalosporins
- Chloramphenicol
- Ciprofloxacin
- Clindamycin
- Clofibrate
- Cocaine
- Danazol
- Enflurane
- Ethambutol
- Ethionamide
- Fenofibrate
- Fluconazole
- Fluoroquinolones
- Foscarnet
- Gentamicin
- Glues
- Heparin
- Herbs and homeopathic therapies like
- Chaparral
- Chinese Herbs
- Gentian
- Germander
- Shark cartilage
- Indomethacin
- Interferon
- Interleukin-2
- Ketoconazole
- Levamisole
- Levodopa
- Lincomycin
- Low-molecular weight heparin
- Methyldopa
- Monoamine oxidase inhibitors
- Naproxen
- Nifedipine
- Nitrofurans
- NMDA
- Non-steroidal anti-inflammatory drugs
- Oral contraceptives
- Phencyclidine
- Phenytoin
- Probenecid
- Procainamide
- Quinine
- Ranitidine
- Retinol
- Ritodrine
- Solvents
- Sulfonylureas
- Tetracycline
- Tobramycin
- Verapamil
Low ALT levels maybe seen in:
- Pyridoxine (vitamin B6) deficiency
Drugs that may decrease the ALT levels include