Laboratory Test (Serum)	Range (Conventional Units)
Alanine aminotransferase	1-45 U/L
Aspartate aminotransferase	1-36 U/L
Alkaline phosphatase
Adult	35-150 U/L
Adolescent	100-500 U/L
Child	100-350 U/L
Bilirubin
Conjugated	0.1-0.4 mg/dL (1.7-6.8 mmol/L*)
Total	0.3-1.1 mg/dL (5.1-19.0 mmol/L*)

*International system of units. Normal values may vary in different clinical laboratories. Adapted from Borer WZ. Reference intervals for the interpretation of laboratory tests. In: Rakel RE, ed. Conn's Current Therapy. Philadelphia, Pa: WB Saunders Co; 1996:1197-1198.

Table II. Causes of Increased Serum Bilirubin Levels

Unconjugated
Hemolysis Immature enzyme systems Physiologic jaundice of newborn Jaundice of prematurity Inherited defects Gilbert syndrome Crigler-Najjar syndrome Drug effects

Conjugated

Hepatocellular disease Cirrhosis Hepatitis Drugs Intrahepatic cholestasis Drugs Pregnancy Benign postoperative jaundice Sepsis Congenital hyperbilirubinemia Dubin-Johnson syndrome Rotor's syndrome Obstructive jaundice Extrahepatic Intrahepatic

Adapted from Friedman LS, Martin P, Munoz SJ. Liver function tests and the objective evaluation of the patient with liver disease. In: Zakim D, Boyer TD, eds. Hepatology: A Textbook of Liver Disease. 3rd ed. Philadelphia, Pa: WB Saunders Co; 1996:791-833.

Table III. Clinical Approach to the Patient With Jaundice

Type of Jaundice
Diagnostic Factors	Hemolytic	Hepatocellular	Intrahepatic Cholestatic	Extrahepatic
Cholestatic
Symptoms	May be asymptomatic or backache, joint pain	Nausea, vomiting, fever, anorexia	Deep jaundice, dark-colored urine, light-colored stools, pruritus	Deep jaundice, dark-colored urine, light-colored stools, pruritus cholangitis, biliary colic
Physical findings	Splenomegaly	Tender hepatomegaly,* splenomegaly	Tender hepatomegaly	Hepatomegaly, palpable gallbladder
Liver tests
Bilirubin
Total	<6 mg/dL	Variable	Variable, may be >30 mg/dL	<30 mg/dL
Direct	<20%	>50%	>50%	>50%
Alanineaminotransferase	Normal	>5-fold increase	2- to 5-fold increase	<2- to 3-fold increase; >3- to 5- fold increase with cholangitis
Alkaline phosphatase	Normal	<2- to 3-fold increase	>3- to 5-fold increase	>3- to 5-fold increase
Prothrombin time	Normal	Prolonged	Prolonged	Prolonged
Corrected by vitamin K	----	No	Variable	Yes
Ultrasonography of liver
Biliary dilatation	No	No	No	Yes
Endoscopic retrograde cholangiopancreatography	Not necessary	Not necessary	Usually not necessary	Usually necessary

*May or may not be present. Reprinted with permission from Kamath PS. Clinical approach to the patient with abnormal liver test results. Mayo Clin Proc. 1996;71:1089-1095.

Table IV. Typical Rangeof Elevated Aminotransferase Levels (AST AND ALT) in Various Liver Diseases

Mild Elevation (<3-fold)

Fatty liver Nonalcoholic steatohepatitis Chronic viral hepatitis

Moderate Elevation (3- to 20-fold) Acute viral hepatitis Chronic viral hepatitis Alcoholic hepatitis Autoimmune hepatitis

Severe Elevation (>20-fold)

Viral hepatitis Drug- or toxin-induced hepatitis Ischemic hepatitis

AST = aspartate aminotransferase; ALT = alanine aminotransferase.

Table V. Agents Reported to Cause Elevations in Liver Enzyme Levels

Medications

Antibiotics Antiepieptic drugs HMG-CoA reductase inhibitors Sulfonylureas NSAIDs

Herbs and Alternative Remedies

Chaparral Chinese herbs Gentian Scutellaria (skullcap) Germander Alchemilla Senna Shark cartilage

Substances of Abuse and Toxins

Anabolic steroids Cocaine 58 Methoxy-3,4 methylenedioxy Methamphetamine hydrochloride (Ecstasy) Phencyclidine hydrochloride (angel dust) Glues and solvents containing toluene Trichloroethylene, chloroform Amanita phalloides toxin

HMG-CoA = 3-hydroxy-3-methylglutaryl coenzyme A; NSAIDs = nonsteroidal anti-inflammatory drugs. Modified from Pratt DS, Kaplan MM. Evaluation of abnormal liver-enzyme results in asymptomatic patients. N Engl J Med. 2000;342: 1266-1271, with permission