Type of test Blood
 Normal findings
 Adult/child: 4-36 units/L at 37° C, or 4-36 units/L (SI units)
 Elderly: may be slightly higher than adult
 Infant: may be twice as high as adult
Test explanation and related physiology
 ALT is found predominantly in the liver; lesser quantities are found in the kidneys, heart, and skeletal muscles. Injury or dis ease affecting the liver parenchyma causes a release of this hepatocellular enzyme into the bloodstream, thus elevating serum ALT levels. Generally, most ALT elevations are caused by liver disease. Therefore this enzyme is not only sensitive but also very specific in indicating hepatocellular disease. In hepatocellular disease other than viral hepatitis, the ALT/AST ratio (De Ritis ratio) is less than 1. In viral hepatitis, the ratio is greater than 1. This is helpful in the diagnosis of viral hepatitis.
Interfering factors
• Previous IM injections may cause elevated levels.
* Drugs that may cause increased ALT levels include acetaminophen, allopurinol, aminosalicylic acid (PAS), ampicillin, azathioprine, carbamazepine, cephalosporins, chlordiazepoxide, chlorpropamide, clofibrate, cloxacillin, codeine, dicumarol, indomethacin, isoniazid (INH), methotrexate, methyldopa, nafcillin, nalidixic acid, nitrofurantoin, oral contraceptives, oxacillin, phenothiazines, phenylbutazone, phenytoin, procainamide, propoxyphene, propranolol, quinidine, salicylates, tetracyclines, and verapamil.
Procedure and patient care
 • See inside front cover for Routine Blood Testing.
 • Fasting: no
 • Blood tube commonly used: red
• Patients with liver dysfunction often have prolonged clotting times.
Abnormal findings
 Increased levels
-Hepatitis
- Hepatic necrosis
 Hepatic ischemia
 Cirrhosis
 Cholestasis
 Hepatic tumor
Hepatotoxic drugs
Obstructive jaundice
Severe burns
Trauma to striated muscle
 Myositis
Pancreatitis
Myocardial infarction
 Infectious mononucleosis
Shock