Q1. CHOLESTATIC JAUNDICE

Definition

Pathophysiology

• Unconjugated bilirubin: insoluble, albumin-bound, cannot be excreted in urine. Accumulates in hemolysis, immaturity of conjugating enzymes.
• Conjugated bilirubin: water-soluble, loosely albumin-bound, excreted in urine. Accumulates in cholestasis and hepatocellular disease.

• Hepatocellular disease
• Bile duct injury
• Biliary obstruction

Clinical Features

• Yellow discoloration of skin and sclera (icterus)
• Pruritus (from bile salt deposition in skin)
• Skin xanthomas (focal cholesterol accumulation)
• Intestinal malabsorption: deficiencies of fat-soluble vitamins A, D, E, and K
• Dark urine (conjugated bilirubin is water-soluble and excreted in urine)
• Pale/acholic stools (absence of bile pigment in gut)

Laboratory Findings

• Elevated serum alkaline phosphatase (ALP) - present on apical membranes of hepatocytes and cholangiocytes
• Elevated gamma-glutamyl transpeptidase (GGT)
• Elevated conjugated (direct) bilirubin
• Prothrombin time may be prolonged (vitamin K malabsorption)

Causes

Extrahepatic (Obstructive) Causes

• Adults: cholelithiasis (gallstones - most common), tumors (carcinoma of head of pancreas, cholangiocarcinoma), postsurgical strictures
• Children: biliary atresia, cystic fibrosis, choledochal cysts, paucity of bile duct syndromes

Intrahepatic Causes

• Primary biliary cirrhosis (PBC)
• Primary sclerosing cholangitis (PSC)
• Drug-induced cholestasis
• Intrahepatic cholestasis of pregnancy
• Neonatal hepatitis

Morphology (Robbins)

1. Bile pigment accumulation in hepatic parenchyma - elongated green-brown plugs of bile in dilated bile canaliculi
2. Feathery degeneration of hepatocytes - droplets of bile pigment accumulate within hepatocytes giving a fine, foamy appearance
3. Kupffer cell hypertrophy - bile extravasated from ruptured canaliculi is phagocytosed by Kupffer cells
4. Apoptotic hepatocytes - occasional

• Distension and dilation of upstream bile ducts
• Ductular reactions at portal-parenchymal interface
• Stromal edema and neutrophils at portal tracts

• Influx of periductular neutrophils into bile duct epithelium and lumen - this is the hallmark

• Periportal fibrosis
• Feathery degeneration of periportal hepatocytes with Mallory hyaline bodies
• Bile infarcts (due to detergent effects of extravasated bile)
• Eventually: secondary biliary cirrhosis (obstructive biliary cirrhosis)

Neonatal Cholestasis

1. Cholangiopathies - primarily biliary atresia (requires surgical intervention)
2. Neonatal hepatitis - metabolic, toxic, genetic, infectious causes (surgery contraindicated)

Q2. SEROLOGICAL MARKERS OF HEPATITIS B AND DIAGNOSTIC SIGNIFICANCE

HBV Genome and Antigens Produced

Serological Markers and Their Diagnostic Significance

1. HBsAg (Hepatitis B Surface Antigen)

• First marker to appear in serum - appears before onset of symptoms
• Peaks during symptomatic disease
• Normally becomes undetectable within 12 weeks (may persist up to 24 weeks)
• Persistence beyond 6 months = chronic HBV infection / carrier state
• Used in vaccine preparation
• Significance: Screening test for HBV; its persistence indicates chronicity

2. Anti-HBs (Antibody to HBsAg)

• Appears after acute disease resolves, a few weeks to months after HBsAg disappears - this gap is the "window period" where neither HBsAg nor anti-HBs is detectable
• Persists for life - confers immunity
• Appears after vaccination
• NOT produced in cases progressing to chronic liver disease
• Significance: Indicates recovery, immunity (natural or vaccine-induced); its absence in chronically infected patients confirms failure to clear infection

3. HBcAg (Hepatitis B Core Antigen)

• Not detectable in serum - remains within hepatocytes, participates in virion assembly
• Detected only in liver biopsy tissue
• Significance: Intrahepatic marker; anti-HBc antibodies (not HBcAg itself) are the key serum markers

4. Anti-HBc (Antibody to HBcAg)

IgM Anti-HBc

• Becomes detectable shortly before onset of symptoms, concurrent with elevated serum aminotransferases
• The key marker in the window period (when HBsAg has disappeared but anti-HBs has not yet appeared)
• Over months, IgM anti-HBc is replaced by IgG anti-HBc
• Significance: Indicates acute/recent HBV infection; only marker present during window period

IgG Anti-HBc

• Replaces IgM anti-HBc over several months
• Persists indefinitely in both recovered and chronically infected individuals
• Part of "total anti-HBc"
• Significance: Indicates past exposure to HBV (cannot distinguish acute from chronic by itself)

5. HBeAg (Hepatitis B e Antigen)

• Appears in serum soon after HBsAg - signifies active viral replication and high infectivity
• Persistence of HBeAg = indicator of progression to chronic hepatitis
• Significance: Marker of high viral replication and infectivity; its persistence predicts chronicity

6. Anti-HBe (Antibody to HBeAg)

• Appearance of anti-HBe implies acute infection has peaked and is waning
• Seroconversion from HBeAg to anti-HBe = favorable sign (reduced replication)
• Significance: Indicates declining viral replication; favorable prognostic sign in acute infection

7. HBV DNA

• Appears soon after HBsAg - most sensitive marker of active viral replication
• Detected by PCR
• Persists in chronic infection
• Used to monitor antiviral therapy response
• Significance: Gold standard for assessing viral load and treatment response

Serological Patterns Summary Table

Clinical Outcomes of HBV Infection (Robbins)

1. Acute hepatitis with recovery and viral clearance
2. Nonprogressive chronic hepatitis
3. Progressive chronic disease ending in cirrhosis
4. Fulminant hepatitis with massive liver necrosis (~0.1-0.5%)
5. Asymptomatic "healthy" carrier state

• Neonates infected perinatally: ~90% risk of chronicity
• Adults acutely infected: only 5-10% risk of chronicity