GIT + Liver
On this page 14 sections
One Liners
- Hepatocellular carcinoma = Aspigillososis
- Cystic Fibrosis = Resistant to cholera
- Gall bladder pain in neck = due to sensory supply from mid cervical dermatome
- Primary biliary cirhosis = Anti mitochondrial antibodies
- Alfatoxin B1 = Hepatocellular carcinoma
LFTs
| Test | What it mainly indicates | When ↑ |
|---|---|---|
| ALT (Alanine aminotransferase) | Hepatocellular injury | Hepatitis, toxins, ischemia, fatty liver |
| AST (Aspartate aminotransferase) | Hepatocellular injury, but also muscle | Hepatitis, alcohol, muscle injury, ischemia |
| ALP (Alkaline phosphatase) | Cholestasis / bile duct injury | Biliary obstruction, cholestasis; also bone disease |
| GGT (γ-glutamyl transferase) | Cholestasis; helps identify hepatic source of ALP | Biliary disease, alcohol, enzyme-inducing drugs |
| 5′-Nucleotidase | Cholestasis / hepatobiliary disease | Biliary obstruction; helps confirm hepatic ALP |
| Bilirubin | Excretory function / hemolysis depending on fraction | Hepatocellular disease, obstruction, hemolysis |
Mallory Denk Bodies
Standard Pathological Concept: Mallory-Denk bodies (eosinophilic intracytoplasmic inclusions composed of damaged intermediate filaments) are classic features seen in:
- Alcoholic liver disease (most common)
- Nonalcoholic steatohepatitis (NASH)
- Wilson’s disease
- Primary biliary cholangitis / Secondary biliary cirrhosis
- Hepatocellular carcinoma (HCC)
Gastrectomy
Bilirubin
| Prehepatic | Hepatic | Posthepatic | |
|---|---|---|---|
| Main problem | ↑ RBC breakdown | Liver dysfunction | Bile obstruction |
| Bilirubin | Unconjugated ↑ | Mixed | Conjugated ↑ |
| Urine bilirubin | ❌ | May ↑ | ↑↑ |
| Urine urobilinogen | ↑ | Variable | ↓/absent |
| Stool | Normal/darker | Variable | Pale/clay |
| ALP | Normal | Mild/moderate ↑ | ↑↑↑ |
| AST/ALT | Normal | ↑↑ | Mild/moderate ↑ |
Whipple Disease vs Giardiasis vs Amoebiasis
| Feature | Whipple disease | Giardiasis | Amoebiasis |
|---|---|---|---|
| Organism | Tropheryma whipplei | Giardia lamblia | Entamoeba histolytica |
| Type | Gram-positive actinobacterium | Protozoan | Protozoan |
| Main site | Small intestine | Duodenum/jejunum | Colon |
| Transmission | Fecal–oral | Fecal–oral, contaminated water | Fecal–oral |
| Main symptom | Malabsorption | Foul-smelling greasy diarrhea | Bloody diarrhea/dysentery |
| Fat malabsorption | Yes | Yes ⭐ | Usually not dominant |
| Weight loss | Yes | Yes | Variable |
| Abdominal pain | Yes | Yes/bloating | Yes |
| Blood in stool | Usually no | No | Yes ⭐ |
| Fever | Usually absent | Usually absent | May occur |
| Extraintestinal features | Arthralgia, lymphadenopathy, neurologic/cardiac involvement | Mainly GI | Liver abscess ⭐ |
| Classic histology | PAS-positive macrophages | Trophozoites/cysts | Flask-shaped ulcers |
| Classic MCQ clue | PAS+ macrophages in small bowel | "Camping/travel + greasy diarrhea" | Liver abscess + bloody diarrhea |
Hirschsprung disease
Clinical Explanation:
- Pathophysiology:
- Hirschsprung disease (congenital aganglionic megacolon) is caused by the failure of neural crest cells to migrate caudally during embryonic development (weeks 5 to 12).
- This results in an absence of enteric ganglion cells (Auerbach’s and Meissner’s plexuses) in the distal colon/rectum, preventing normal intestinal peristalsis and relaxation.
- Classic Presentation:
- Failure or delay to pass meconium within the first 24 to 48 hours of life.
- Signs of lower intestinal obstruction: abdominal distension, bilious vomiting, and squirt sign (explosive release of gas/stool upon digital rectal exam).
- Gold-Standard Diagnosis:
- Suction rectal biopsy showing the absence of ganglion cells in the submucosa and myenteric plexus, accompanied by hypertrophied nerve trunks.
Hyperlidipemia
| Type | Elevated Lipoprotein | Main Lipid Elevated | Typical Cause | Clinical Features |
| I | Chylomicrons | Triglycerides | Lipoprotein lipase deficiency | Pancreatitis, eruptive xanthomas |
| IIa | LDL | Cholesterol | Familial hypercholesterolemia (-LDL receptors) | Tendon xanthomas, premature CAD |
| IIb | LDL + VLDL | Cholesterol + TG | Familial combined hyperlipidemia | Common in metabolic syndrome |
| III | IDL (beta–VLDL) | Cholesterol + TG | ApoE2 homozygosity | Palmar xanthomas |
| IV | VLDL | Triglycerides | Familial hypertriglyceridemia, obesity, DM, alcohol | Most common type, associated with insulin resistance |
| V | VLDL + Chylomicrons | TG + Cholesterol | Mixed hyperlipidemia | Pancreatitis risk |
Chloride sweat test (for Cystic Fibrosis)
1. Pathophysiology:
◦ Cystic Fibrosis (CF) is an autosomal recessive disorder caused by mutations in the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) gene.
◦ Defective chloride transport leads to thick, viscous mucosal secretions obstructing various organ systems.
2. Key Presentation:
◦ Respiratory System: Recurrent sinopulmonary infections (sinusitis, otitis media, pneumonia/bronchitis).
◦ Gastrointestinal / Pancreas: Exocrine pancreatic insufficiency causing malabsorption, severe chronic diarrhea (steatorrhea), and failure to thrive.
3. Confirmatory Diagnostic Test:
◦ The quantitative pilocarpine iontophoresis sweat test (sweat chloride test) is the diagnostic gold standard for confirming CF when sweat chloride concentration is > 60 mmol/L.
Atresia / Stenosis
| Condition | Key Clinical Features / Triad | Typical Age of Onset | Key Pathophysiology |
| Esophageal Atresia | • Drooling / excessive salivation ("pouring of saliva") • Immediate choking & regurgitation with first feed | Right after birth (Day 1) | Esophagus ends in a blind pouch; swallowed saliva & milk cannot reach the stomach. |
| Duodenal Atresia | • Bilious (green) vomiting • Abdominal distension • Double bubble sign on X-ray | First 24–48 hours of life | Failure of duodenum to recanalize; obstruction is distal to the ampulla of Vater. Associated with Down syndrome. |
| Pyloric Stenosis | • Non-bilious projectile vomiting • Continuous hunger after vomiting • Palpable "olive-shaped" abdominal mass | Typically 3 to 6 weeks of age | Hypertrophy of the pyloric sphincter muscle causing gastric outlet obstruction. |
Cellular level
Here is an explanation of when each of the cellular pathologies in the options typically takes place:
1. Plasma Membrane Damage (Correct Answer)
- When it occurs: In early, sublethal, or ongoing liver injury—such as acute viral hepatitis, toxic insult, or acute ischemia.
- Mechanism: Transaminases (ALT and AST) are intracellular enzymes stored inside the cytoplasm of hepatocytes. When hepatocytes suffer injury, the integrity of the plasma membrane is disrupted or becomes permeable, allowing these enzymes to leak out into the circulation.
- Clinical Significance: You do not need complete cell destruction/death for ALT and AST to spill into the blood; simple loss of plasma membrane integrity is sufficient to cause marked enzyme elevations.
2. Mitochondrial Damage
- When it occurs: During severe, irreversible cell injury, ischemia-reperfusion injury, or toxin-mediated toxicity (e.g., severe acetaminophen toxicity or alcohol-induced liver injury).
- Mechanism:
- Disruption of inner mitochondrial membrane potential leads to loss of the mitochondrial permeability transition pore (MPTP), halting ATP production.
- Leakage of Cytochrome c from the mitochondria into the cytosol activates the caspase cascade, triggering apoptosis or necrotic cell death.
- In the liver, mitochondrial AST (mAST) is specifically released into the serum during heavy alcohol intake or severe necrosis, contributing to an AST:ALT ratio >2:1.
3. Lysosome-Mediated Cell Destruction
- When it occurs: During the late stages of cell necrosis (autolysis) or during controlled degradation pathways like autophagy and phagocytosis.
- Mechanism:
- In necrosis, severe cellular swelling leads to the rupture of lysosomal membranes, spilling potent acid hydrolases (proteases, nucleases, lipases) directly into the cytoplasm, which digests the internal organelles of the dying cell.
- In inflammatory conditions, macrophages and neutrophils release lysosomal enzymes to clean up dead cellular debris.