Hepatology Flashcards
Functionality of the liver
bile production (for digestion of foods + activation of pro drugs)
drug/food/toxin metabolism
protein synthesis (including albumin - for oncotic pressure in vascular system, and coagulation factors)
storage/adjustment of vitamins/gluconeogenesis
Liver is heavily integrated into
GI system and is important for perfusion from the heart + vasculature system
Objective markers
aspatate transaminase
alanine transaminase
alkaline phosphatase
bilirubin
albumin
international normalized ratio
thrombocytopenia
Aspartate transaminase (AST)
increases with acute liver injury
Alanine transaminase (ALT)
increases with acute livery injury
Alkaline phosphatase (alk phos)
increases with biliary tract injury from acute liver injury (i.e. gallstone)
Bilirubin
increases with biliary tract injury from acute liver injury (i.e. gallstone) or chronic liver disease
Albumin
decreases with chronic liver disease, malnutrition, CKD, or acute inflammation
International normalized ratio (INR)
increases with chronic liver disease, warfarin, or malnutrition
Thrombocytopenia
decreases with chronic liver disease, HIT, or malignancy
Objective assessment summary
term LFTs are not true markers of liver fx: liver enzymes (AST, ALT, Alk phos) usually markers of acute liver injury
elevated bilirubin can be a sign of acute and/or chronic liver issues
chronic liver disease can decrease liver production of proteins resulting in: decreased albumin, increased INR, and/or increased bilirubin
What is the estimated incidence of drug-induced liver injury (DILI)?
14-19 cases per 100,000 persons
0.02%
What are the mechanisms/classifications of the different types of DILI?
direct
indirect
idiosyncratic
Direct
agents that are intrinsically toxic to the liver
ex. acetaminophen
Indirect
caused by the action of the drug (what it does)
ex. inducing metabolite abnormalities causing non-alcoholic fatty liver disease/steatotic liver disease
Idiosyncratic
agents that have little or no intrinsic toxicity and that cause liver injury only in rare cases
ex. beta lactams, fluoroquinolones, macrolides
What medications are highest risk for causing DILI?
acetaminophen
anti-infectives: isoniazid, beta lactam antibiotics (penicillins, cephalosporins), fluoroquinolone antibiotics, macrolide antibiotics
If suspect DILI
hold offending agent
monitoring not recommended at baseline for most (except isoniazid as will be used for months)
Acetaminophen DILI
acute ingestion of high doses (>/= 8g acetaminophen) can result in toxic levels of N-acetyl-p-benzoquinone imine (NAPQI), which causes direct heptaotoxicity
s/sx: abdominal pain, jaundice, N/S/diarrhea
if not managed, can induce irreversible liver damage
assess severity through AST, ALT, and acetaminophen concentration
Goal of acetaminophen toxicity
reverse toxic metabolite through use of N-acetylcysteine (NAC) +/- activated charcoal (only if ingested <1hr prior, prevents absorption but not if taken more than 1 hr prior)
N-acetylcysteine (NAC) MOA
binds NAPQI, decreaasing hepatotoxic effects
NAC mimics or restores glutathione –> helps conjugate NAPQI to a non-toxic metabolite (cysteine and mercapturic acid) –> can be excreted (no hepatotoxicity)
NAC indication/monitoring
based on concentration of acetaminophen (>/= 4 hours after ingestion) and timing since ingestion
NAC use determined by rumack-matthew nomogram - give NAC if level is above solid line
monitor: liver enzymes - AST/ALT (q12-24h) and s/sx
PO = IV in efficacy
Acetaminophen DILI summary
assess timing of ingestion
using APAP concentration from lab and timing of ingestion, determine need for NAC using rumack-matthew nomogram
monitor liver enzymes + s/sx of acute liver injury
if intentional overdose, psychiatry evaluation appropriate
Cirrhosis
severe, chronic, irreversible fibrosis of the liver: associated with increased morbidity and mortality; annual mortality risk is 10% or more
complications are related and increase with severity (ex. hepatorenal syndrome)
Causative factors of cirrhosis
chronic alcohol use (#1 in US) - stop drinking, can prevent progression, but can’t reverse what’s been done
viral hepatitis
metabolic liver disease (ex. hemochromatosis, nonalcoholic steatohepatitis)
cholestatic liver disease (ex. primary biliary cirrhosis)
drugs: chronic use of amiodarone, methotrexate
S/sx of cirrhosis
pruritus
fatigue
weight loss
ascites
juandice (accumulation of bilirubin)
hepatomegaly or splenomegaly
encephalopathy (confusion)
Cirrhosis complications
ascites, esophageal varices, hepatic encephalopathy, spontaneous bacterial peritonitis, thrombocytopenia, hyponatremia, hepatorenal syndrome