Hepatic Enzyme Elevations and Their Significance

Question 1

Alanine aminotransferase (ALT,
formerly known as SGPT)

Answer 1

Measure of hepatic cellular enzymes found in circulation, elevated when hepatocellular damage is present.

Highly liver specific. This enzyme has circulatory half-life of 37–57 hr; levels increase relatively slowly in response to hepatic damage and clear gradually after damage ceases. See AST for contrast in this rise and fall pattern.

Question 2

Alanine aminotransferase (ALT,
formerly known as SGPT)

Answer 2

In hepatitis A, B, C, D, or E, or drug-associated or industrial chemical–associated hepatitis, ALT usually increases higher than AST, with enzyme increases ≥10 times ULN.

Question 3

Alanine aminotransferase (ALT,
formerly known as SGPT)

Answer 3

In nonalcoholic fatty liver steatohepatitis
(NASH, also known as nonalcoholic fatty liver disease [NAFLD]), ALT usually increases higher than AST, with enzyme increases usually within 3 times ULN.

Question 4

Alanine aminotransferase (ALT,
formerly known as SGPT)

Answer 4

A 22 y.o. woman with acute
hepatitis A
AST 678 U/L (normal 0–31 U/L)
ALT 828 U/L (normal 0–31 U/L)
ALT:AST ratio ≥1

Question 5

Alanine aminotransferase (ALT,
formerly known as SGPT)

Answer 5

A 66 y.o. woman with obesity,
type 2 diabetes mellitus, and
nonalcoholic fatty liver disease
AST 44 U/L
ALT 78 U/L
ALT:AST ratio >1

Question 6

Aspartate aminotransferase (AST,
formerly known as SGOT)

Answer 6

Measure of hepatic cellular enzymes found in circulation, elevated when hepatocellular damage is present. Enzyme also present in lesser amounts in skeletal muscle and myocardium.

Question 7

Aspartate aminotransferase (AST,
formerly known as SGOT)

Answer 7

AST has circulatory half-life of ~12–24 hr; levels increase in response to hepatic damage and clear quickly after damage ceases.

Question 8

Aspartate aminotransferase (AST,
formerly known as SGOT)

Answer 8

In alcohol-related hepatic injury AST usually increases higher than ALT.

Question 9

Aspartate aminotransferase (AST,
formerly known as SGOT)

Answer 9

In acetaminophen overdose, massive
increases in AST and ALT are often
noted, ≥20 times ULN.

Question 10

Aspartate aminotransferase (AST,
formerly known as SGOT)

Answer 10

A 38 y.o. man with a 10-yr history
of increasingly heavy alcohol use
AST 83 U/L (normal 0–31 U/L)
ALT 50 U/L (normal 0–31 U/L)
AST:ALT ratio ≥1

Question 11

Aspartate aminotransferase (AST,
formerly known as SGOT)

Answer 11

A 26 y.o. man with intentional
acetaminophen overdose
AST 15,083 U/L (normal 0–31 U/L)
ALT 10,347 U/L (normal 0–31 U/L)

Question 12

Alkaline phosphatase (ALP)

Answer 12

Levels increase in response to biliary obstruction and are a sensitive indicator of intrahepatic or extrahepatic cholestasis

Question 13

Alkaline phosphatase (ALP)

Answer 13

Enzyme found in rapidly dividing or metabolically active tissue, such as liver, bone, intestine, placenta.

Elevated levels can reflect
damage or accelerated cellular division in any of these areas.

Most ALP in circulation is of
hepatic origin.

Question 14

Alkaline phosphatase (ALP)

Answer 14

A 40 y.o. woman with acute
cholecystitis
AST 45 U/L (0–31)
ALT 55 U/L (0–31)
ALP 225 U/L (0–125)

Question 15

Gamma glutamyl transferase

GGT

Answer 15

In liver disease, usually parallels changes in alkaline phosphatase. Marked elevation
often noted in obstructive jaundice, hepatic metastasis, intrahepatic cholestasis.

Question 16

Gamma glutamyl transferase

GGT

Answer 16

Enzyme involved in the transfer of amino acids across cell membranes. Found primarily in the liver and kidney.

Question 17

Gamma glutamyl transferase

GGT

Answer 17

A 40 y.o. woman with acute
cholecystitis
AST 45 U/L (0–31)
ALT 55 U/L (0–31)
ALP 225 U/L (0–125)
GGT 245 U/L (0–45)