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GI LAB MED > Liver Enzymes > Flashcards

Liver Enzymes Flashcards

1
Q

What are the liver associated enzymes?

A 
AST - Aspartate aminotransferase
ALT - Alanine aminotransferase
AP - Alkaline Phosphatase
Bilirubin (total, direct, indirect)
Gamma glytamyl transpeptidase (GGT)
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2
Q

Hepatocellular injury vs. Cholestatic

A

Hepatocellular –> AST and ALT

Elevated at least 3x their normal of 40 (higher in men, lower in women)

AP remains NORMAL

Cholestatic –> AP will be at least 2-3 x higher than normal (125); AST and ALT pretty normal

If MIXED injury, all 3 messed up and higher

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3
Q

R Values

A

Calculate how many times above normal ALT is
Calculate how many times above normal AP is
Divide first answer, by 2nd answer

R > 5 means HEPATOCELLULAR

R < 2 means CHOLESTATIC

between 2-5 -> MIXED

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4
Q

AST vs. ALT

A

Leak out of injured hepatocytes

AST half life is nearly 3x longer than ALT half life –> these enzymes can be higher at different times

AST can be found in OTHER TISSUES –> skeletal and cardiac muscle, renal tissue, brain, pancreas, WBC

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5
Q

Acute Viral Hepatitis

A

SUPER HIGH AST and ALT

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6
Q

Bilirubin and AST/ALT

A

Presence of jaundice/bilirubin does NOT correlate with AST and ALT

Bilirubin, if increased at all, often LAGS BEHIND AST and ALT elevations

Even when the patient is recovering (AST and ALT lowering), the bilirubin may still be RISING

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7
Q

Acute Liver FAILURE

A

If patient has a rapid DECREASE in ALT and AST and does NOT develop coagulopathy or encephalopathy (confusion) it is usually a sign of RECOVERY

BUT, if there is a rapid decrease and the patient DOES have coagulopathy or encephalopathy –> ACUTE LIVER FAILURE!!!!!

40-50% of the time due to acetaminophen

Liver is spent and can’t even make these enzymes!

Note that bilirubin can still be increasing

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8
Q

HIGH LEVELS

A

Drug induced liver injury –> typically won’t risk above 2000

Acute Viral HEP A and B –> 4000-6000

Acute Viral HEP C –> < 2000

ULTRA HIGH (> 6000)

Acetaminophen (#1)
Shock liver (#2)
Toxic Mushrooms
Chemical Toxins

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9
Q

ALT > AST

A

Nonalcoholic Steatohepatitis – NASH –> a fancy term for liver disease NOT caused by alcohol

Any type of CHRONIC viral hepatitis

DRUGS

Metabolic conditions (hemochromatosis, Wilson’s (Copper), Alpha-1-Antitrypsin Deficiency, Autoimmune Hepatitis)

ALT is much more liver specific

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10
Q

ALCOHOL, AST & ALT

A

ALCOHOL!!! AST will ALWAYS be higher than ALT for Alcohol!!!!

AST will be 2-3x higher than the ALT

**ABSOLUTE CEILING for ALCOHOL –> AST will NEVER NEVER NEVER > 300 in this cause

ALT will NEVER NEVER NEVER be > 100 in this case****

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11
Q

GGT

A

Elevated in ACTIVE DRINKERS

Gamma-Glutamyl Transpeptidase

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12
Q

Other where AST > ALT

A

Besides alcohol…

TRANSFORMATION TO CIRRHOSIS –> say an active Hep C patient (chronic) always has ALT > AST and then next visit has AST > ALT –> CIRRHOTIC LIVER

SHOCK LIVER –> Absolute values > 6000!!!! AST always higher than ALT

LDH (lactate dehydrogenase) will also be higher than ALT in this case

Associated MUSCLE injury –> AST made in muscle

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13
Q

AP Significantly elevated (1000-2000) by itself, NO AST/ALT CHANGE

A

Differential has to include:

SARCOIDOSIS (inflammatory disease that causes granuloma formation)

TUMOR IN THE LIVER

BILE DUCT OBSTRUCTION

AIDS CHOLANGIOPATHY

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14
Q

GGT Elevation (alone)?

A

ALCOHOL or DRUGS!!!!

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15
Q

Evaluating Jaundice/Cholestasis, INTRAHEPATIC

A

Chronic Cholestasis –> Can go on for many years –> PRIMARY biliary cirrhosis, Primary Sclerosing Cholangitis, Sarcoidosis, Drugs that injure the bile duct

Acute Cholestasis –> rapid elevation of AP with or without AST/ALT:

GALLSTONES
Post-operative Cholestasis
Pregnancy
Sepsis

Obstruction of biliary tree? Extrahepatic

DILATED BILE DUCTS = OBSTRUCTION

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16
Q

Acutely Severe AST/ALT (above 1000)…

A 
Viral Hepatitise
Drugs
Acute bile duct obstruction
Vascular liver disorders like BUDD-CHIARI (occulsion of hepatic veins)
Acute Autoimmune Hepatitis
Ischemic Hepatitis/Shock liver (> 6000)
17
Q

Chronically elevated AST/ALT (300 or less)

A

Hepatitis viruses that can become chronic (HBV, HCV, HDV)
Autoimmune hepatitis…
Non-alcoholic Fatty Liver Disease (NASH)
Metabolic Diseases (hemochromatosis, celiac, A1ATD, Wilson’s)

18
Q

Non-Hepatic Causes of AST and ALT Elevations

A

Celicac
Thyroid disorders (hypo and hyper)
Muscle injury (Rhabdomyolysis – AST > ALT)
Macro-AST – benign

19
Q

Post-Op Elevated BIlirubin

A

Could be caused by –> HEMOLYTIC ANEMIA from multiple blood transfusions during a long surgery

GILBERT’S SYNDROME - benign condition of a deficiency in the enzyme that conjugates bilirubin (5% of pop)

Resorbing hematoma –> also seen after MAJOR SURGERIES and the bilirubin is mostly INDIRECT (nothing wrong with liver)

20
Q

Drug Induced Liver Injury

A

Can mimic all forms of acute and chronic liver disease, including vascular and neoplastic causes; same with cholestatic and mixed injuries

Liver will be able to adapt to these elevations after a while

Hepatocellular Injury WITH jaundice DUE TO A DRUG –> 10% risk of death! —> Hy Zimmerman’s Law of Hepatotoxicity

Common causes of DILI –> Antibiotics, Anti-epileptic drugs, Anti-TB drugs, Herbals, NSAIDs, Propothiouracil (for hyperthyroidism!)

21
Q

HAV

A

HAV-IgM antibody in the blood

22
Q

HBV

A

Hep B Surface Antigen (HGsAg) and a CORE IgM antibody

If both positive, HBV acute

E antigen (eAg) + if the virus actively replicating

EXCLUDE HBV with a negative HBsAg OR a negative Core IgM

23
Q

HCV

A

Cannot produce antibodies (IgM or IgG) against HCV for at least a few weeks-months after exposure

For acute HCV, need to see VIRAL RNA in the blood

24
Q

HDV

A

Must ALREADY BE INFECTED WITH HBV!!!!

Must have +HBsAg, +Core IgM, +AntiHDV as well

Can be part of a SUPERINFECTION, which would mean acute HDV on top of CHRONIC HBV (switch core IgM or +Core IgG

25
Q

HEV

A

Commonly presents as acute drug injury – 10-20% of what are thought to be acute drug injury are actually HEV

26
Q

AUTOIMMUNE HEPATITIS

A

Nobody knows why it happens, but the body attacks its own liver

Type 1 –> mostly ADULTS; will have +ANA, +ASMA (anti-smooth muscle); many have other autoimmune disorders; 50% cirrhosis

Type 2–> Not seen in US as much; PEDIATRIC VERSION –> children will be positive for Liver-Kidney-Microsomal Antibody (LKM1); Early cirrhosis common

Type 3 –> Positive for soluble liver antigen (SLA); EXTREMELY RARE

Can often overlap with AUTOIMMUNE CHOLANGITIS (high AP, AST, ALT)

27
Q

3 Fatty Liver Diseases NOT caused by Alcohol

A

Non-Alcoholic Steatohepatitis (NASH) –> associated with CHRONIC HEPATITIS and features BIG DROPLETS of FAT in the liver, ELEVATED ALT (alcoholic have AST > ALT!!!!) –> 25% progress to Cirrhosis

Non-alcoholic Fatty Liver –> implies fatty liver disease WITHOUT CHRONIC HEPATITIS; obese, diabetics, drug users

Non-Alcoholic Fatty Liver Disease —> same as NASH? …cool

28
Q

Indirect Elevated Bilirubin (adults)

A

HEMOLYTIC ANEMIA (RBCs get broken down before getting to liver)

GILBERT’S SYNDROME –> Patients will have NO SIGNS OF ANEMIA (diff than Hemolytic anemia)

Kids? Crigler Najjar Syndrome –> fatl

29
Q

DIRECT elevated bilirubin

A

Dubin-Johnson Syndrome and Rotor’s Syndrome

both benign

30
Q

MELD SCORE

A

Model for End Stage Liver Disease

Takes patients CREATININE, BILIRUBIN, INR into account as a measure of renal and liver fxn

HIGH SCORE means WORSE SURVIVAL WITHOUT A TRANSPLANT in the next 90 DAYS

MELD > 20 = TRANSPLANT NEEDED!!!

31
Q

Alcoholic Hepatitis

A

AST > ALT, but NEVER above 300 (AST) or 100 (ALT)

32
Q

Acute Viral Hepatitis

A

Elevated and nearly equal, but not > 10,000 (still pretty damn high)

AP normal

33
Q

Acetaminophen

A

SUPER HIGH LFTs

Phase 1 of overdose is < 24 hours after ingestion – may feel sick, but LFTs normal

Phase 2 of overdose is > 24 hours –> can feel ok but MUCH worse a day later when LFTs spike (>10,000!!!)

34
Q

Sarcoidosis?

A

AP ELEVATED

Bilirubin doesn’t have to be elevated

Remember - Bilirubin DOES NOT DEFINE HEPATOCELLULAR or CHOLESTATIC

35
Q

NASH CIRRHOSIS?

A

AST > ALT, but not as much as alcohol (remember alcohol AST is 2-3x HIGHER than ALT)

AP less than 2x normal

36
Q

Gilbert’s Syndrome?

A

Indirect Bilirubin is Elevated

Since indirect, AST and ALT normal

37
Q

Mixed Injury?

A

R Value between 2-5

Take ALT, how many times above normal
Take AP, how many times above normal
Divided top by bottom

38
Q

Primary Sclerosing Cholangitis

A

PURE CHOLESTATIC INJURY, So JUST AP MESSED UP

39
Q

Acute Passage of Gallstone?

A

MIXED injury

Elevated AST, ALT, AP

GI LAB MED (2 decks)

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