WEEK 5 - Hepatic Disorders Flashcards
What is the purpose of the hepatic portal system?
- Allows the liver to take out glucose for storage after meals
- Allows toxic molecules to be partially detoxified before blood moves on to the heart
What is hepatitis?
Inflammation of the liver characterised by:
Hepatomegaly Poor appetite Abdominal discomfort Abnormal liver function Jaundice Clay coloured stool Tea coloured urine
What are the causes of hepatitis?
Infection - viral, bacterial, parasitic
Alcohol
Drugs and toxins
Transfusion of incompatible blood
Characteristics of Hep A?
- RNA virus
- Transmitted via faecal-oral route (contaminated food/water)
- Asymptomatic infection in children
- High risk groups: travellers, men who have sex with men
Characteristics of Hep B?
- Transmitted parenterally, sexually and perinatally
- DNA virus
- Becomes chronic after six months
- The earlier the age of infection the greater the likelihood of carrying it for life
Characteristics of Hep C?
- RNA virus
- Effects intravenous drug users (spread parenterally)
- Becomes chronic after 6 months
- Can cause liver failure if left untreated
- Only 1 in 4 will recover
Characteristics of Hep D?
- RNA virus
- Can only occur in people with Hep B
- Can be prevented with Hep B vaccine as they share molecules of their viral coats
- Causes a more severe infection
- Spread parenterally, sexually and perinatally (same as Hep B)
Characteristics of Hep E?
- No vaccine, has many strains
- Linked to undercooked meat and seafood
- Spread via faecal-oral route
Characteristics of Hep G?
- Structurally similar to Hep C
- Little or no symptoms
- Spread parenterally, sexually and perinatally
What is the pathophysiology of hepatitis?
- Causes direct cellular injury: necrosis and scarring of hepatocytes, hyperplasia and infiltration by mononuclear phagocytes
- Leads to an immune response that damages and obstructs the bile ducts
What clinical manifestations occur in acute fulminating hepatitis?
Necrosis
Encephalopathy
Liver failure
Death
Clinical testing for hepatitis?
- Abnormal LFTs = raised AST (aspartate transaminase) and ALT (alanine transaminase)
- ALP = biliary system obstruction (lines the biliary duct)
- LFTs may be in normal range in chronic liver disease
Describe the four stages of hepatitis
- Incubation period - most infectious during this time
- Prodromal phase - early, non specific syndrome: fatigue, GI disturbances, weight loss, anorexia, headache, rash, fever, jaundice (last step)
- Icteric phase - jaundice, yellow skin, itching, tea coloured urine, clay coloured stool, fatigue, hepatomegaly
- Recovery phase - jaundice and other S&S subside, liver function returns to normal, full recovery in most people
Diagnosis of hepatitis?
Not based on symptoms alone as they are nonspecific
- Blood tests for virus-specific antibodies
- HBsAg - Hep B specific antigen
LFTs for liver function indication
Treatment for acute viral hepatitis?
- Restriction of physical activity
- Low fat and high carb diet
- Smaller, more frequent meals to spread out metabolism
- Hand washing and avoid contact with bodily fluids
(no real treatment)
Treatments for chronic hepatitis?
- HepB: treatments to slow progression
- HepC: curable with 95% success rate
What is hepatic encephalopathy?
- Neurological impairment secondary to hepatic dysfunction
- Characterised by neural disturbances due to increased ammonia levels
How does ammonia cause neural disturbances?
- Ammonia is a byproduct of protein metabolism
- Inability of the liver to detoxify ammonia = ammonia build up = reaches the brain via the BBB
- Ammonia is metabolised into glutamine - interferes with neurotransmitters, astrocyte oedema = brain herniation, oedema, death
Diagnosis of hepatic encephalopathy?
- Hx of liver disease in addition to:
- Signs and symptoms
- Blood tests (for high ammonia levels)
Treatment for hepatic encephalopathy?
- Fluid and electrolyte correction
- Restrict dietary protein
- Neomycin (eliminates bacteria for protein metabolism)
- Lactulose (promotes excretion of ammonia)
What is liver cirrhosis?
Occurs at the end of chronic liver disease
Irreversible inflammatory condition where liver tissue is replaced by dysfunctional fibrotic tissue
What are the different types of liver cirrhosis?
- Alcoholic cirrhosis
- Biliary cirrhosis
- Post-necrotic cirrhosis
- Metabolic cirrhosis
Pathophysiology of liver cirrhosis?
Poorly understood
- Fibrosis due to inflammation and necrosis
- Functional hepatocytes replaced by scarred nodules
- Leads to a hard, dysfunctional liver
- Obstruction to vascular network reduces the blood flow to the liver and may lead to portal hypertension
- Biliary duct obstruction leads to bile stasis and leakage of bile = necrosis of hepatocytes, jaundice and pain
Pathophysiology of alcoholic cirrhosis?
Metabolism of alcohol produces acetaldehyde = damages hepatocytes, causes inflammation