Liver Function Biochemistry PDF

Hepatic Function The liver is essential for metabolism, detoxification, protein synthesis, and bile production > 2 suggests alcoholic liver disease...

Hepatic Function The liver is essential for metabolism, detoxification, protein synthesis, and bile production > 2 suggests alcoholic liver disease Enzymes like ALT (Alanine aminotransferase) and **Hepatocellular Injury** Tests measure AST **Transaminases levels** AST (Aspartate aminotransferase) leak into the hepatocyte damage AST/ALT > 1000 indicates severe necrosis bloodstream when liver cells are damaged Elevated > 4x suggests bile duct injury Elevated Alkaline phosphatase (ALP) or **Bile Flow & Duct Injury** Tests assess the **Alkaline Phosphatase (AP)** Gamma-glutamyl transferase (GGT) suggests bile pathway's integrity bile flow blockage or duct injury Mild elevation may be extrahepatic (e.g., bones, kidneys) **Synthetic Capacity** Evaluates the liver’s For eg, low levels of albumin and prolonged Increased in alcohol consumption and certain drugs **Gamma-glutamyl Transferase (GGT)** Interpreting Liver Function Tests Liver Function Biochemical Tests **Types of Tests** ability to produce vital substances prothrombin time indicate reduced synthesis Direct (conjugated): Cholestasis **Bilirubin** **Cirrhosis & Complications** Advanced tests Multi-parametric evaluation analyze disease staging and complications Indirect (unconjugated): Gilbert’s syndrome or hemolysis **Etiology of Liver Disease** Additional tests Albumin < 3 g/dL = Chronic liver disease Determined via viral serology, toxins, or determine specific causes, like infections or **Albumin & Prothrombin Time** metabolic markers toxins Prothrombin time > 3 sec = Synthetic dysfunction **Plasma Proteins** Reflect liver's protein synthesis Diagnosed via serology: Anti-HAV, Anti-HCV, Anti-HBc, PCR **Viral Hepatitis** ALT (Liver-specific injury marker) Hemochromatosis (Iron overload) Etiology of Liver Diseases Elevated levels indicate obstruction in bile Key Tests and Measurements **Enzymes** AST (Liver and non-liver injury) pathways Wilson’s Disease (Copper accumulation) **Metabolic Diseases** Alpha-1 antitrypsin deficiency Liver Function ALP, GGT (Bile obstruction or cholestasis) Biochemistry Mind **Bilirubin** Total bilirubin includes both direct (conjugated) and indirect (unconjugated) forms. Its increase may signal liver dysfunction, hemolysis, or bile obstruction Causes: Toxins (e.g., paracetamol), infections, Map **Acute Liver Disease** alcohol In chronic liver disease or severe acute damage, Decreased synthesis: liver disease Prolonged liver cell destruction and impaired Severe and Chronic Liver Disease the liver can't produce sufficient albumin regeneration lead to permanent damage **Chronic Liver Disease** Protein loss: From conditions like nephrotic Cirrhosis is the end-stage, where normal liver tissue is syndrome or protein-losing enteropathy replaced with scar tissue, losing functionality **Hypoalbuminemia** Lack of raw materials (e.g., amino acids) Malnutrition or malabsorption Increased breakdown: Occurs in trauma or Excess bilirubin in blood causes yellow skin and postoperative states eye discoloration Causes of Serum Abnormalities Overhydration or genetic variations **Pre-hepatic**:Excess bilirubin production due to hemolysis Hepatobiliary diseases Liver conditions directly elevate AST/ALT **Hepatic**: Liver’s inability to process bilirubin due to damage or enzyme deficiencies **Types** Jaundice AST is found in muscles, heart, and pancreas, so **Elevated Transaminases** Myocardial, pancreatic, or muscle diseases non-liver conditions (e.g., myocardial infarction) can elevate it **Post-hepatic**: Biliary obstruction prevents bilirubin excretion Alcohol or toxins Cause specific liver damage patterns Erythrocyte degradation, liver damage, biliary obstruction **Causes** **Globin**: Reused amino acids Manifestations: Yellowing of skin and eyes Red blood cells (120-day lifespan) degraded into: **Heme**: Converted into bilirubin Unconjugated bilirubin binds to albumin Bilirubin and Heme Degradation **Heme Breakdown** **Unconjugated Bilirubin**: (lipophilic) for liver transport Most conjugated bilirubin is eliminated in bile, In the liver, bilirubin is conjugated with glucuronic **Conjugated Bilirubin**: converting to stercobilin (brown pigment in acid, making it hydrophilic for excretion feces) and urobilin (yellow pigment in urine)