Liver & Biliary Tree Enzymes: ALT, AST, ALP Flowchart

Modern liver imaging includes MRI for detecting fat content and elastography for measuring liver stiffness without needle biopsy. The FIB-4 index (using age, AST, ALT, and platelet count) predicts fibrosis risk, with values above 1.5 suggesting increased fibrosis risk. The key therapeutic goal is preventing fibrosis progression, as research shows that individuals with fatty liver but without fibrosis have similar longevity to those without fatty liver. Those with both fatty liver and fibrosis have significantly shorter life expectancy.

For abdominal ultrasound examinations, patients should fast for 6-8 hours before the procedure and avoid drinking water, as food and liquid in the stomach can interfere with the ultrasound imaging of abdominal organs.

Diagnostic imaging for biliary obstruction includes: (1) Abdominal ultrasound (non-invasive, shows dilations, tumors, stones, parenchymal abnormalities), (2) CT scan (more specific/sensitive but uses contrast dye), (3) MRCP (magnetic resonance cholangiopancreatography - excellent visualization of biliary tree without radiation), and (4) ERCP (endoscopic retrograde cholangiopancreatography - invasive, therapeutic, used for stone extraction and sphincterotomy). ERCP involves passing a catheter through the mouth to the ampulla of Vater. Complications include acute pancreatitis (most common), cholangitis, duodenal perforation, and papillary bleeding.

Multiple imaging modalities are available for evaluating biliary obstruction: (1) Ultrasound is the initial screening tool, detecting indirect signs of obstruction such as common bile duct dilation (normal <8mm in non-pregnant patients); (2) CT scan is valuable for evaluating periampullary tumors (head of pancreas, ampulla of Vater, distal common bile duct) and staging malignancy; (3) MRCP (Magnetic Resonance Cholangiopancreatography) is the gold standard for non-invasive visualization of the entire biliary tree, highly sensitive and specific for detecting stones; (4) Endoscopic Ultrasound (EUS) provides excellent resolution for detecting small stones near the ampulla; (5) ERCP (Endoscopic Retrograde Cholangiopancreatography) is both diagnostic and therapeutic but carries risks of pancreatitis (10% complication rate). The choice depends on clinical suspicion, available resources, and whether intervention is anticipated.

Laboratory interpretation requires understanding normal ranges and patterns. Bilirubin total and direct must be evaluated together. Alkaline phosphatase and GGT elevation suggests biliary obstruction, as these enzymes are released by bile duct epithelium when obstructed. The combination of elevated enzymes supports obstructive pathology. Imaging modalities include ultrasound (first-line, visualizes stones and measures duct diameter >8mm), MRCP (high sensitivity/specificity for ductal visualization), ERCP (gold standard for diagnosis and treatment), CT, and HIDA scan. Each technique serves specific purposes based on clinical context and patient factors.

Hepatoprotectors include essential phospholipids, ursodeoxycholic acid, and dimethylglycine. Diuretic therapy for ascites begins with spironolactone (up to 200mg daily), adding furosemide if ineffective. Beta-blockers (propranolol, atenolol) reduce portal pressure and prevent variceal bleeding. Extracorporeal detoxification methods support decompensated patients. Etiotropic treatment includes antiviral therapy (lamivudine, tenofovir) for hepatitis B. Surgical interventions include endoscopic variceal ligation, sclerotherapy, balloon tamponade, radiofrequency ablation, and TIPS (transjugular intrahepatic portosystemic shunt). Liver transplantation remains the definitive treatment for end-stage cirrhosis.

Management of gallstone disease depends on symptom severity and stone type. Medical management includes: ursodeoxycholic acid for dissolving cholesterol stones; pain management with ketorolac/tramadol for mild pain and morphine/demerol for severe pain (morphine contraindicated as it can cause sphincter of Oddi spasm); antispasmodics like buscopan to relieve smooth muscle spasms; and metoclopramide for nausea/vomiting (contraindicated in pregnancy). Surgical management involves cholecystectomy (gallbladder removal), with laparoscopic approach being the standard. Emergency surgery is required for complications like perforation or peritonitis. Post-ERCP nursing care includes maintaining NPO status until gag reflex returns and monitoring for perforation and allergic reactions to iodine-based dye.

The liver parenchyma lacks pain receptors, so liver tissue damage rarely causes pain; right upper quadrant pain typically originates from the capsule or adjacent structures. Drug-induced liver injury can occur from medications previously considered safe, and herbal remedies can be hepatotoxic despite being perceived as safe. Hepatitis A is transmitted fecal-orally and rarely causes chronic disease. Hepatitis B and C are the leading causes of chronic viral hepatitis and cirrhosis. Hepatitis B has an effective vaccine providing long-lasting protection and can prevent hepatocellular carcinoma. Hepatitis C treatment has been revolutionized by direct-acting antivirals achieving 95% cure rates in 12 weeks. Gallbladder removal is indicated for symptomatic gallstones and complications; gallstones can be dissolved using ursodeoxycholic acid under specific conditions. Cirrhosis is characterized by fibrosis disrupting normal liver architecture; treatment depends on etiology and decompensation involves ascites, variceal bleeding, and hepatic encephalopathy. Adequate protein intake improves survival, and salt restriction is more important than fluid restriction for ascites management.

ERCP (endoscopic retrograde cholangiopancreatography) is both diagnostic and therapeutic for bile duct obstruction. The endoscope is passed through the mouth to the duodenum, allowing direct visualization of the biliary tree and stone extraction. Surgical treatment depends on the cause: gallstones may be managed with ERCP or surgery, malignancy may require resection or palliative stenting. Hepaticojejunostomy is performed when the common bile duct is too narrow or damaged. Direct hepaticojejunostomy is rare and technically challenging.

Treatment of liver disease requires targeted approaches based on etiology. Hepatoprotective agents act through various mechanisms: membrane stabilization (phosphatidylcholine derivatives), anti-inflammatory effects (silymarin/milk thistle), antifibrotic activity, and stimulation of regeneration. Ursodeoxycholic acid (13-15 mg/kg/day) is recommended for cholestatic liver diseases, NAFLD/NASH, and gallstone dissolution. Choleretic drugs modify bile composition to prevent stone formation. Lactulose reduces ammonia absorption for hepatic encephalopathy. No single agent addresses all mechanisms, and combination therapy may be necessary. Drug-induced liver injury requires careful medication review and discontinuation of offending agents. Antiviral therapy is indicated for chronic viral hepatitis regardless of cirrhosis presence. Liver transplantation remains definitive treatment for end-stage cirrhosis. Treatment goals include symptom control, complication prevention, and slowing disease progression.

Liver diseases progress through a specific pathway: fatty liver (脂肪肝) → acute hepatitis (急性肝炎) → chronic hepatitis (慢性肝炎) → liver cirrhosis (肝硬変) → hepatocellular carcinoma (肝がん). This progression typically takes 30-40 years. The progression can be visualized through endoscopic examination: normal liver appears smooth, chronic hepatitis shows a rough surface, cirrhosis develops nodules, and hepatocellular carcinoma appears as distinct cancerous nodules.

The liver, known as the 'silent organ,' can sustain damage without noticeable symptoms until significant scarring (cirrhosis) develops; chronic hepatitis is defined as liver inflammation persisting for six months or longer, progressing through stages from inflammation to fibrosis and potentially cirrhosis, where healthy liver tissue is progressively replaced by scar tissue, impairing liver function and potentially leading to complications like ascites and esophageal varices; modern diagnostic approaches now include non-invasive methods such as FibroScan and MR elastography to assess liver stiffness and fibrosis stage, reducing the need for invasive liver biopsy while enabling earlier detection and intervention.

Liver cirrhosis occurs when liver cells are destroyed, causing the liver to gradually become hard. The primary cause is liver fibrosis. Cirrhosis significantly increases the risk of developing liver cancer later in life.

Chronic liver injury leads to progressive fibrosis through repeated cycles of inflammation and repair. Fibrous bands form between portal tracts and central veins, creating architectural distortion. Cirrhosis represents the final common pathway where surviving hepatocyte nodules become surrounded by fibrous tissue. Portal hypertension develops because regenerating nodules and fibrous septa disrupt normal vascular architecture, impeding blood flow through the liver sinusoids. Cirrhosis progresses from micro-nodular (small regeneration nodules) to macro-nodular (fewer, larger nodules) as chronic inflammation continues. This architectural transformation creates the substrate for complications including varices and hepatic encephalopathy.

Liver fibrosis is defined as a fibrotic response in the liver causing accumulation of extracellular matrix components, leading to fibrous scar formation that disrupts liver architecture, causes hepatocyte loss, and deregulates normal liver function. Two main causes trigger this condition: hepatotoxic injury (chronic hepatitis B/C infections, Western diet, alcohol abuse) and cholestatic injury (reduced/obstructed bile flow from primary sclerosing cholangitis or biliary atresia). The disease progresses through stages: chronic liver injury → fibrosis → cirrhosis → hepatocellular carcinoma. Critically, fibrosis is reversible, but cirrhosis is irreversible, necessitating liver transplantation when cirrhosis develops.