Liver function tests

Question 1

AST (SGOT)

Answer 1

[10-45 U/L] aspartate aminotransferase (serum glutamic oxaloacetic transaminase); located in hepatocyte cytoplasm and mitochondria; elevation usually indicates hepatocellular injury; elevation may also indicate skeletal or myocardial muscle injury

Question 2

ALT (SGPT)

Answer 2

[8-40 U/L] alanine aminotransferase (serum glutamic pyruvic transaminase); located in hepatocyte cytoplasm; elevation usually indicates hepatocellular injury; more specific to the liver than AST

Question 3

ALK PHOS

Answer 3

[40-129 U/L] alkaline phosphatase; located on the surface of liver cells adjacent to bile canaliculi; also present in bone, intestine, and placenta; elevation usually indicates biliary obstruction or cholestatic process; definitive origin of elevation is determined by simultaneous GGT levels (elevated GGT indicates biliary origin, normal GGT indicates non-biliary origin)

Question 4

GGT

Answer 4

[0-50 U/L] gamma glutamyl transpeptidase; used to verify the origin of elevated alkaline phosphatase: if elevated alkaline phosphatase AND elevated GGT, then origin is biliary - if GGT is normal, then elevated alkaline phosphatase is due to a non-biliary origin; nonspecific for anything else

Question 5

Bili

Answer 5

[total: 0.2-1.0 mg/dL] [direct: 0-0.2 mg/dL] bilirubin; the product of red blood cell breakdown; unconjugated is water-insoluble, conjugated is water-soluble; elevated conjugated bili indicates liver injury, bile duct problems, or rare metabolic problems; elevated unconjugated bili indicates hemolysis or Gilbert’s; not generally helpful in determining type of liver injury (may be elevated in hepatocellular, cholestatic, or infiltrative disease, as well as non-hepatic disease)

Question 6

PT

Answer 6

prothrombin time

Question 7

INR

Answer 7

[0.9-1.3] international normalized ratio; indicates health of liver synthetic function; may be affected by poor oral nutritional intake or severe infection (if due to nutrition, vitamin K replacement will correct it)

Question 8

albumin

Answer 8

[3.5-5] indicates health of liver synthetic function; may be affected by poor oral nutritional intake, severe infection, proteinuria, or GI loss

Question 9

common causes of hepatocellular damage

Answer 9

alcohol, viral hepatitis, autoimmune hepatitis, hemochromatosis, Wilson’s disease, fatty liver, alpha-1 antitrypsin deficiency, medications

Question 10

common causes of cholestatic/obstructive liver damage

Answer 10

stones, primary biliary cirrhosis, primary sclerosing cholangitis, medications

Question 11

common causes of ALT > 500

Answer 11

Hepatitis A, Hepatitis B, autoimmune hepatitis, medications, ischemia (shock liver), rarely stone passage

Question 12

AST:ALT > 2:1 suggests…?

Answer 12

alcoholic liver disease

Question 13

tests helpful for indicating acute or chronic status of liver injury

Answer 13

INR, albumin