Liver Enzymes Flashcards
(39 cards)
What are the liver associated enzymes?
AST - Aspartate aminotransferase ALT - Alanine aminotransferase AP - Alkaline Phosphatase Bilirubin (total, direct, indirect) Gamma glytamyl transpeptidase (GGT)
Hepatocellular injury vs. Cholestatic
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
R Values
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
AST vs. ALT
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
Acute Viral Hepatitis
SUPER HIGH AST and ALT
Bilirubin and AST/ALT
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
Acute Liver FAILURE
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
HIGH LEVELS
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
ALT > AST
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
ALCOHOL, AST & ALT
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****
GGT
Elevated in ACTIVE DRINKERS
Gamma-Glutamyl Transpeptidase
Other where AST > ALT
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
AP Significantly elevated (1000-2000) by itself, NO AST/ALT CHANGE
Differential has to include:
SARCOIDOSIS (inflammatory disease that causes granuloma formation)
TUMOR IN THE LIVER
BILE DUCT OBSTRUCTION
AIDS CHOLANGIOPATHY
GGT Elevation (alone)?
ALCOHOL or DRUGS!!!!
Evaluating Jaundice/Cholestasis, INTRAHEPATIC
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
Acutely Severe AST/ALT (above 1000)…
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)
Chronically elevated AST/ALT (300 or less)
Hepatitis viruses that can become chronic (HBV, HCV, HDV)
Autoimmune hepatitis…
Non-alcoholic Fatty Liver Disease (NASH)
Metabolic Diseases (hemochromatosis, celiac, A1ATD, Wilson’s)
Non-Hepatic Causes of AST and ALT Elevations
Celicac
Thyroid disorders (hypo and hyper)
Muscle injury (Rhabdomyolysis – AST > ALT)
Macro-AST – benign
Post-Op Elevated BIlirubin
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)
Drug Induced Liver Injury
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!)
HAV
HAV-IgM antibody in the blood
HBV
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
HCV
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
HDV
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
