Ch. 18 4-6 (Dobson) Flashcards
This is defined as a decrease in bile flow due to impaired secretion by hepatocytes or to obstruction of bile flow through intra- or extra-hepatic bile ducts.
Cholestasis
What is the hallmark of cholestasis?
Accumulation of green-brown plugs of bile pigment in hepatocytes and dilated canaliculi.
Hepatic bile serves two major functions, which are…
1) Emulsification of dietary fat in the lumen of the gut through the detergent action of bile salts.
2) Elimination of bilirubin, excess cholesterol, xenobiotics, trace metals, and other waste products that are insufficiently water-soluble to be excreted into urine.
________ is a toxic end product of heme degradation that is processed by the liver and excreted in the bile.
Bilirubin
The majority of bilirubin produced daily is derived from breakdown of senescent _______ by macrophages in the spleen, liver, and bone marrow.
RBCs
Hepatic handling of bilirubin involves uptake from the circulation, intracellular storage, conjugation with _______ _______, and excretion into bile.
Glucuronic acid
Total serum bilirubin levels in the normal adult vary between 0.3 and 1.2 mg/dL. _________ becomes evident when the serum bilirubin levels rise above 2 to 2.5 mg/dL.
Jaundice
What are the types of bilirubin?
Unconjugated (Indirect)
Conjugated (Direct)
Testing for conjugated and unconjugated plasma bilirubin helps determine the cause of hyperbilirubinemia. Excess bilirubin production (ie, due to hemolytic anemia or ineffective erythropoiesis) or defective conjugation (due to immaturity or hereditary causes) leads to the accumulation of _________ bilirubin.
Unconjugated
This form of bilirubin is largely insoluble and cannot be excreted in the urine.
Unconjugated
Although most unconjugated bilirubin is tightly bound to ________ in the blood, at excessive levels the unbound fraction rises and may diffuse into tissues, particularly the brain in infants, producing neurologic damage known as ________.
Albumin
Kernicterus
_________ hyperbilirubinemia most often results from hepatocellular disease, bile duct injury, and biliary obstruction.
Conjugated
This form of bilirubin is water-soluble and loosely bound to serum albumin, so it can be excreted in the urine.
Conjugated
Elevated bilirubin becomes clinically evident as yellow discoloration of the skin, called _______, and sclera, called _______.
Jaundice
Icterus
Other manifestations of cholestatic disease include pruritus, skin ________ (focal accumulation of cholesterol), or symptoms related to intestinal malabsorption, including deficiencies of fat-soluble vitamins.
Xanthomas
These are the characteristic laboratory findings of cholestatic disease. The enzymes are present on the apical (canalicular) membranes of hepatocytes and bile duct epithelial cells.
Elevated serum ALP
Elevated GGT
In physiologic jaundice of the newborn, levels of _______, the enzyme responsible for bilirubin glucuronidation, are low at birth and do not reach adult levels until 3-4 months of age.
UGT1A1
Breastfeeding of a newborn may exacerbate unconjugated hyperbilirubinemia, possibly because of the presence of what enzymes in breast milk?
Bilirubin-deconjugating enzymes
In most infants, what is the treatment to keep unconjugated bilirubin within a safe range? How does it work?
Phototherapy with blue light, which converts bilirubin to a soluble isomer that is readily excreted in the urine.
This disease is autosomal recessive and contains mildly low UGT activity. This results in increased unconjugated bilirubin. Overall patients usually don’t have problems, but they can develop jaundice during times of stress like during an infection.
Gilbert Syndrome
This disease has an absence of UGT, resulting in increased unconjugated bilirubin. Results in kernicterus and is usually fatal.
Crigler-Najjar Syndrome I
***Type II has decreased UGT, very similar to Gilbert!
This is an autosomal recessive disease that is due to a deficiency of bilirubin canalicular transport protein. There is a mutation in the protein MRP2. This causes increased conjugated bilirubin. It is not clinically significant but there is deposition of brown-black melanin-like pigment in the hepatocytes and can lead to blackening of the liver.
Dubin-Johnson Syndrome
***Liver conjugates the bilirubin but can’t move it anywhere!
This disease is similar to Dubin-Johnson but does NOT have the blackening of the liver.
Rotor Syndrome
This disease causes inflammation that disrupts hepatocytes and small bile ductules, causing both conjugated and unconjugated bilirubin to increase. The urine is dark due to increased urine bilirubin, but urine urobilinogen is normal or decreased.
Viral hepatitis
In adults, cholestasis is usually due to 3 types of large duct obstructions, which are…
1) Stones
2) Tumors
3) Strictures
What is the term for gallstones in the common bile duct?
Choledocholithiasis
Resulting cholestatic changes are reversible if the obstruction is corrected early in the disease course, but persistent obstruction can lead to fibrosis and so-called biliary _________.
Cirrhosis
Biliary obstruction also predisposes to ________ _______, a bacterial infection of the biliary tree most commonly caused by enteric organisms such as coliforms and enterococci. Usually presents with fever, chills, abdominal pain, and jaundice. Severe cases can result in abscess formation, sepsis, and death.
Ascending cholangitis
Acute (ascending) cholangitis is a bacterial infection of the biliary tract as a result of obstruction. Invasion of bacteria is from the duodenum. Patients with this will present with Charcot’s Triad, which is what?
1) Jaundice
2) RUQ Pain
3) Fever
Acute suppurative cholangitis is the presence of pus in the biliary ducts (due to the bacteria from the duodenum). This may result in Reynold’s Pentad, which is what?
Charcot’s Triad = Jaundice, RUQ pain, Fever
+
Hypotension and Confusion
Sepsis may affect the liver in what main ways?
– Intrahepatic infection (abscess formation, bacterial cholangitis)
– Ischemia (related to hypotension caused by sepsis, especially when liver is cirrhotic)
– Microbial products (most likely to lead to the cholestasis of sepsis)
This is a disease of intrahepatic gallstone formation that leads to repeated bouts of ascending cholangitis, progressive inflammatory destruction of hepatic parenchyma, and predisposes to biliary neoplasia (Cholangiocarcinoma). The area of highest prevalence is East Asia.
Primary hepatolithiasis
Prolonged conjugated hyperbilirubinemia in the neonate affects approx. 1 in 2500 live births. Since physiologic jaundice of the newborn usually resolves by two weeks, infants who have jaundice beyond 14-21 days after birth should be evaluated for…
Neonatal Cholestasis
There are 2 broad categories of Neonatal Cholestasis, which are what?
- Obstructive
- - Nonobstructive
What are the obstructive causes of Neonatal Cholestasis?
Biliary atresia
What are the nonobstructive causes of Neonatal Cholestasis?
- Paucity of bile ducts (Alegielle syndrome)
- Infectious/metabolic
- Genetic (bile transporter defects)
- Idiopathic
Without surgical intervention, this is the most common cause of Neonatal Cholestasis and death from liver disease in early childhood.
Biliary atresia
This is characterized as a complete or partial obstruction of the lumen of the extrahepatic biliary tree within the first 3 months of life. Accounts for 1/3 of neonatal cholestasis cases and for 50-60% of children referred for liver transplantation.
Biliary atresia
There are 2 forms of biliary atresia, which are…
– Perinatal (80% – Infection/toxin/autoimmune)
– Fetal (20% – commonly associated with anomalies resulting from ineffective establishment of laterality of thoracic and abdominal organs during development)
This is the surgical procedure performed performed for biliary atresia. The intestine is attached to the liver, which allows bile to drain.
Kasai procedure
Explain how one liver could save 2 lives?
Livers can be divided into two parts that can each grow to the full organ in about a month. Smaller portion is cut off and given to a child, while the larger portion is given to an adult.
What are the types of autoimmune hepatitis (AIH)?
Type 1 (Adults) Type 2 (Children)
What are the types of autoimmune cholangiopathies?
PBC (Primary Biliary Cirrhosis/Cholangitis)
PSC (Primary Sclerosing Cholangitis)
In a small subset of AIH patients, there may be overlap with other autoimmune liver diseases, in particular _______ or _______ (the latter most often occurring in the pediatric setting). Diagnosis of “overlap” syndromes requires full display of both clinical and histologic features of AIH and the other, concomitant disease.
PBC
PSC
Autoimmune diseases tend to be (ACUTE/CHRONIC) diseases and the damage is often progressive. Sometimes autoimmune diseases are associated with relapses and remissions. The clinical and pathologic manifestations are determined by the nature of the underlying immune response.
Chronic
Autoimmunity arises from a combination of the inheritance of susceptibility _______, which may contribute to the breakdown of self-tolerance, and _________ triggers, such as infections and tissue damage, which promote the activation of self-reactive lymphocytes.
Genes
Environmental
Among the genes known to be associated with autoimmunity, the greatest contribution is that of ______ genes.
HLA
AIH has a strong association with specific HLA alleles in Caucasians (_____), Japanese (_____), and in South Americans (_____).
DR3
DR4
DRB1
The lymphocytic infiltrate in the ever of patients with AIH is composed predominantly of _______ cells with _______ cells at the interface.
CD4+ helper T cells
CD8+ cytotoxic T cells
For AIH, CD4+ cells play an important role in activating B lymphocytes and their differentiation into plasma cells, which are responsible for production of ________. The mechanism by which the interplay of lymphocytes, autoAbs, and HLA types lead to liver injury is unclear.
AutoAbs