GI Exam: Liver Flashcards
What is hepatitis?
•Inflammation of the liver
•Associated with elevation of liver enzymes
–AST and ALT (indicate liver injury)
–Other Liver Tests (“LFTs”) which can be abnormal in hepatitis include: Bilirubin, alkaline phosphatase, gamma glutamyl transpeptidase
What are common causes of acute hepatitis?
All less than 6 months of abnormal tests!
•Viruses – hepatotropic – A through E
•Viruses – CMV, EBV, HSV
•Other infectious etiologies - TB, MAI, Fungus
•Alcoholic hepatitis
•Drug induced liver injury ( DILI)
•Ischemic hepatitis
•Biliary disease – e.g. choledocholithiasis
Are the hepatitis viruses DNA or RNA?
HAV, HCV, HDV, and HEV are all positive sense, single stranded RNA
HBV is double stranded, circular DNA
What are symptoms of acute viral hepatitis?
- Fatigue, nausea, anorexia
- Yellow eyes / skin, dark urine
- Acholic stool
- Low-grade fever, abdominal pain
- Arthralgia, myalgia, headache
- Rarely associated with confusion and an INR greater than 1.4 (that would be acute liver failure)
- Jaundice
- Hepatomegaly with RUQ tenderness
What are the common AST and ALT seen in acute viral hepatitis? Bilirubin? Alk phos? Urine bilirubin?
AST and ALT 500-5,000
Bilirubin mildly elevated (1.5+ mg/dl)
Alk phos mildly elevated
How is hep A transmitted? When can it be spread?
Fecal-oral; has a 1 month incubation period and can be shed 2 weeks before symptoms start; children are asymptomatic
How does hep A progress?
Never causes chronic hepatitis, but can cause acute liver failure (typically in patients who have preexisting liver disease)
What is the serological course of HAV?
ALT elevated 1 month after exposure, then resolves; IgM is + for approx 5-6 months; anti-HAV then elevated forever (makes patient immune)
How is hep A treated?
No anti-viral
Vaccinate! (age 1-40)
Passive immunity using gamma globulin can help to ameliorate disease in early stages of infection or can prevent disease post-exposure (use in patients at extremes of ages - infants and 41+ y/o)
Who should be vaccinated for HAV?
travelers to endemic areas MSM IV drug abusers health care workers patients with chronic liver dz possibly day care workers
Which HBV genotype is associated with HCC?
HBV C
Where is HBV most prevalent?
Africa, Asia
At what age is the development of HBV typically acute? Chronic?
Infants and young children likely will develop chronic HBV; older children and adults will either clear it or have acute illness
How is HBV transmitted?
horizontally (sexual, parenteral, secretions)
vertically (mother to child)
6-8 week incubation
If HBV is cleared, which antigens/antibodies will stay positive?
surface antigen will clear along with infection and become negative
core antibody will be positive
surface antibody will be positive
anti-HBc IgM will become negative
Which tests are positive in chronic HBV?
anti-HBc IgG
surface antigen
What does positive IgM mean?
Acute infection
What are the 5 stages of HBV?
- minimal inflammation, immune tolerant (high viral load, low ALT)
- active inflammation, immune activation (ALT increases and viral load decreases - actively fighting infection)
- mild inflammation, low replicative (slightly elevated ALT, low viral load)
- reactivation, active inflammation (increased ALT AND increased viral load)
- inactive, remission (looks like #3)
Which patients with HBV should be screened for HCC?
•Hepatitis B carriers at high risk –All cirrhotic hepatitis B carriers –Family history of HCC –Asian males 40+ years of age –Asian females 50+ years of age –Africans 20+ years of age –High HBV DNA levels and ongoing hepatic inflammatory activity –Platelet count less than 170,000/μL Perform liver US every 6-12 months
Why can HCV now be cured?
HCV genome is not converted to DNA and exists in host cytoplasm as RNA, which is less stable
How does HCV progress?
6-8 week incubation period
Acute infection generally mild
80% develop chronic disease
Treatment now cures 90+%
What are ALT levels like in HCV?
During acute infection, levels may be close to 1000 - later they typically bounce around 200
What is hepatitis D?
–Also known as delta agent
–Uses the HBsAg protein coat
–Hepatitis B must be present – coinfection or preexisting
–Can cause Acute Hepatitis when patients are simultaneously infected with HBV and HDV, this can progress to cirrhosis
–Can cause “acute on chronic” hepatitis when patients with chronic HBV get superinfected with HDV
–Therapy directed against HBV
What is hepatitis E?
•Behaves like HAV ( feco-oral spread)
•Causes endemic and self-limited hepatitis
–Can cause acute liver failure in pregnant women
–rare chronic hepatitis in immunocompromised patents
•Found predominantly in developing world (typically genotype I and II), but does occur in developed world (usually III and IV)
Reliable assay not found in US
What does the liver do?
- Conjugation and secretion of bilirubin
- Synthesis and secretion of plasma proteins (including clotting factors and albumin)
- Metabolism of drugs and alcohol
- Carbohydrate metabolism
- Protein/nitrogen metabolism
- Cholesterol/lipid/bile salt metabolism
What are the sources of bilirubin?
early peak (20%, in the first 20 days): ineffective erythropoiesis, hepatic heme turnover late peak (80%, 120-160 days): destruction of RBCs in spleen
What’s the deal with bilirubin and solubility?
Bilirubin is highly insoluble in blood (soluble in fat) b/c of intramolecular hydrogen bonding - blocks exposure of polar groups to aqueous solvents
Major consequence of bilirubin metabolism in liver is to make it more polar (water soluble).
What is the process of bilirubin in blood and liver?
Bound to albumin in blood
Taken up into hepatocytes at the sinusoidal membrane
Conjugated to glucuronic acid
Bilirubin glucuronide is secreted from hepatocytes by an ATP-binding cassette protein (rate-limiting step; disrupted in acquired liver dz)
What happens to bilirubin in hepatocyte dysfunction?
May see increase in urobilinogen in urine because it is less efficiently reabsorbed by hepatocytes
What happens to bilirubin in biliary obstruction?
–Stools may appear white because bilirubin does not get into intestine and therefore not converted to stercobilins/urobilins
–No urobilinogen detected in urine
Is more bilirubin conjugated or unconjugated?
Vast majority is unconjugated
What abnormal tests might you see in liver dysfunction?
- Elevated serum bilurubin concentration (jaundice)
- Prolonged prothrombin time (bleeding tendency)
•Low serum albumin (edema)
•Altered metabolism of drugs/induced liver damage
•Hypoglycemia/other carbohydrate abnormalities
•Increased blood concentration of ammonia and nitrogenous metabolites (encephalopathy)
•Altered blood lipids and elevated bile salts
When do you see primary unconjugated hyperbilirubinemia?
Overproduction, impaired intake by hepatocytes and impaired conjugation
- hemolysis, ineffective erythropoesis, sepsis, drugs
When do you see primary conjugated hyperbilirubinemia?
Impaired secretion of bilirubin diglucuronide by hepatocytes and biliary obstruction
- cirrhosis, acute hepatitis, pregnancy, birth control pills
- tumors, sclerosing cholangitis, gallstones, primary biliary cirrhosis
What is neonatal jaundice caused by?
Immaturity of all steps in bilirubin metabolism
Note: High blood concentrations of lipid soluble unconjugated bilirubin in infants that also have poorly developed blood-brain barrier can lead to kernicterus (brain damage caused by bilirubin deposition)
Why does putting infants under the bili lights work?
Causes a change in conformation - Less intramolecular hydrogen bonding of E diasteriomers make them more aqueous soluble for renal excretion.
What is the blood supply to the liver?
Dual blood supply
–Hepatic artery – direct from heart
–Portal vein - drains gut (first pass metabolism)
Why do you see hypoglycemia in liver failure?
Hypoglycemia occurs in severe end stage liver disease (cirrhosis) and acute liver failure because of inability to adequately perform glycolysis and gluconeogenesis
•Patients with advanced liver disease (cirrhosis) also often have hyperglycemia, possibly because of decreased ability of liver to store glycogen
What does ammonia have to do with liver function?
Encephalopathy and increased blood ammonia
ammonia is probably not the actual cause, but is instead a sign
not detoxifying nitrogen products, affects the brain (patients describe it is living in a cloud - recall is low, thinking isn’t as sharp, fair amount of confusion)
What does the liver synthesize?
- Heme biosynthesis
- Iron metabolism
- Copper metabolism
- Vitamin A storage
- Vitamin D metabolism
What are hepatocytes and what do they do?
Well differentiated cells that make up 80% of the cytoplasmic mass; cells have the ability to replicate when activated by injury
- Secrete bile acids
- Take up digested material
- Synthesize albumin
- Metabolize and detoxify exogenous compounds
Why do albumin and PT evaluate different things?
PT: production of several coagulation factors is in the liver. Most have half-lives between 6-96 hours; prolonged within a day with hepatic synthetic dysfunction
Albumin: produced in the hepatocytes; half life is 20 days but not specific; can be abnormal because of the other factors that can lower
Where is alk phos found?
A family of isoenzymes that catalyze the hydrolysis of phosphate esters
Found in liver, bone, intestine, placenta, kidney, leukocytes
In liver associated with sinusoidal and canalicular membranes
Obstruction to bile flow causes an increase in AP secondary to the induction of AP synthesis
Where is AST found?
Mitochondria and cytosol of hepatocytes, heart, and muscle
Where is ALT found?
Cytosol of hepatocytes
Which elevations are seen in lab tests in hepatocellular disease?
AST and ALT significantly elevated
alk phos, bilirubin, GGT slightly elevated
Which elevations are seen in lab tests in cholestatic disease?
AST, ALT, GGT slightly elevated
alk phos and bilirubin significantly elevated
Which elevations are seen in lab tests in infiltrative disease?
AST, ALT, GGT, bilirubin slightly elevated
alk phos way out of wack (very elevated - out of proportion)
What can ultrasound do for liver evaluation?
Biliary tree: - rule out obstruction - evaluate for the presence of stones Vasculature: - Evaluate flow and rule out obstruction - Screen for thrombus - Screen for stricture
What can MRI do for liver evaluation?
Demonstrates the morphology of the liver
- Evaluate for size, position
- Evaluation for bleeding
- Evaluate for tumors , both benign or malignant
Will not evaluate liver function and is not sensitive enough to detect fibrosis of the liver. Rarely reveals exact etiology of disease
What does ERCP do?
Endoscopic cannulation of the ampulla with injection of contrast into the biliary tree
Diagnosis and therapy
What are the 2 kinds of idiosyncratic drug-induced liver injury?
1: Allergic Reactions
- Fever, rash, eosinophilia
- Latency 1 month or less
- Rapid recurrence after re-exposure
* example-sulfa drugs
- Non-Allergic
- No features of hypersensitivity
- Long latency (often many months)
- Re-challenge does not consistently reproduce the injury
What are the characteristics of acute liver failure?
altered mentation
coagulopathy (INR 1.5+)
acute onset (6 months or less)
no cirrhosis
What is the most common cause of acute liver failure in the US?
acetaminophen toxicity
How should ALF be treated?
- Intensive Care Unit
- Correct complications proactively
- Avoid FFP, sedatives until decision on transplant reached
- Short trial of lactulose may help, but not much and may hurt
- Rapid transplant evaluation, early transfer
What is the link between ALF and infection?
- Seen in 80% of patients, documented bacteremia in 20-25%
- Secondary to gut translocation, decreased RE function and instrumentation
- Gram negatives, Staph and Strep with fungal infection in up to 33%
- All patients should be cultured broadly with low threshold for empiric antibiotics
- Consider prophylactic antifungals if renal failure or on antibiotics
What is the link between ALF and renal failure?
- Occurs in up to 33% of patients
- Often multifactorial – volume depletion, ATN, hepatorenal
- Urine sodium may be helpful in determining cause
- Avoid CT contrast, empiric aminoglycosides
- Since patients tolerate volume overload poorly, CVP or PA monitoring important
What is the biggest concern with ALF?
Multi-organ failure
• Peripheral vasodilatation with hypotension, pulmonary edema, acute tubular necrosis, and disseminated intravascular coagulation
• Difficult to separate from sepsis
• Can be a contraindication to liver transplant
• Treatment is supportive only
What is the link between ALF and cerebral edema?
Present in up to 80% of patients dying with FHF
Difficult to diagnose with CT, early monitoring essential
If untreated, can lead to herniation – transplantation the only “cure”
Hypertonic saline and hypothermia new standard of care, but data limited
What is the MELD score?
- Based on log of the bilirubin (jaundice), INR (clotting time) and creatinine (kidney function)
- Developed to predict death after TIPS
- Best predictor of 3 month risk of dying on waiting list for chronic liver disease
- Also predicts death in ALF
What are the indications for liver transplant?
• Patient with End-Stage Liver Disease meeting UNOS listing criteria and having NO significant co-morbid conditions
– Acute Liver Failure
– Any Form of Chronic Liver Failure
• Complications or predicted 1 year survival less than 90%
• Localized primary liver cancer (HCC) with selected criteria (Milan criteria)
What are the contraindications for liver transplant?
- Cancer outside the liver
- Active substance abuse/noncompliance
- No social support
- Diseases that won’t be fixed by a transplant or that will make the surgery too high risk
What are the mandatory tests for transplant evaluation?
- Ultrasound with Dopplers
- HCC Screening (usually CT or MRI)
- Chest X-ray and EKG
- Echocardiogram +/- saline contrast (bubble echo)
- ABG +/- Pulmonary function tests
- Laboratory tests including HIV and ABO blood type
- PPD (TB test)
- Pregnancy test
- Recent PAP smear
- Thallium stress test – over 45, risk factors
- Mammogram - women over 40
- Heart catheterization – abnormal heart tests
- Screening colonoscopy - over 50
How are livers matched?
Blood type (ABO, not +/-) and size
What are the MELD exceptions for liver transplant?
• Stage II HCC, MELD greater than 22 + additional points every 3 months –Most common exception –Increasing value for HCC screening • Hepatopulmonary syndrome • Familial amyloidosis • Ascites with TIPS failure • Recurrent cholangitis
How do you treat HCC?
Put them on list and monitor every 3 months with ultrasound
Can try chemoembolization, radiofrequency ablation
What is the Descriminant Function?
Used to score alcoholic hepatitis
DF 32+ benefits from steroids if no infection or GI bleeding