Tiêu đề Liver Function ✅

The liver produces 3L of bile per day and excretes 1L of what is produced. The primary function of bile is the emulsification of fats 8. Bile canaliculi → Intrahepatic ducts → R and L hepatic ducts → common hepatic duct → Cystic duct → Gallbladder 9. Common hepatic duct merges with the Cystic duct to form the common bile duct. And the common bile duct merges with the pancreatic duct and opens into the duodenum via the ampulla of Vater. 10. Once in the intestines, conjugated bilirubin is reduced into urobilinogen by intestinal bacteria. 11. 80% of urobilinogen is further reduced into stercobilinogen, and is further oxidized to stercobilin which is excreted in the stool. Stercobilin is what gives stool its brown color. 18-19% of urobilinogen enters the enterohepatic circulation to be recycled and excreted. The remaining 1-2% will enter the systemic circulation and will be subsequently filtered by the kidney and excreted in the urine. IMPORTANT NOTES •Approximately 200-300mg of bilirubin is produced per day •Almost all bilirubin formed is eliminated in the feces •Reference values for adults: - Unconjugated bilirubin: 0.2-0.8mg/dL (3-14 umol/L) - Conjugated bilirubin: 0.0-0.2mg/dL (0-3 umol/L) - Total bilirubin (B1+B2): 0.2-1.0mg/dL (3-17 umol/L) JAUNDICE •aka icterus •Usually noticeable to the naked eye if bilirubin is >3mg/dL •Initially seen in the eyes & oral mucosa → skin •Classified based on the site of disorder: - Prehepatic, Hepatic, Posthepatic Conjugated Bilirubin Unconjugated Bilirubin Prehepatic x ↑↑ Hepatic variable variable Posthepatic ↑↑ x PREHEPATIC JAUNDICE •Occurs when the problem causing the jaundice occurs prior to liver metabolism •Most common cause: Hemolytic anemia •Hemolytic anemia causes an increased amount of RBC destruction and subsequent release of increased amounts of bilirubin presented to the liver for processing. •Most important lab finding: Unconjugated bilirubinemia HEPATIC JAUNDICE •Occurs when then the primary problem resides in the liver 1.Gilbert Syndrome - Genetic mutation in the gene UGT1A1 on chromosome 2 - UGT1A1 is responsible for producing UDPGT - Liver conjugation is working at 30% of normal - Total bilirubin usually fluctuates bet 1.5-3.0mg/dL 2. Crigler-Najjar Syndrome - Type 1: Complete absence of UDPGT