Background Information on the Liver References: Clinical Chemistry 4th Ed, Marshall Biochemistry in Clinical practice, Williams & Marks Diagnostic Strategies 2nd Ed, Black, Bordley, Tape & Panzer Role of liver: Central role in intermediary metabolism and is also responsible for detoxification of many foreign compounds, deamination of amino acids and synthesis of urea, synthesis and secretion of bile, metabolism of some hormones, synthesis of plasma proteins and storage of certain vitamins.
Structure The main blood supply to the liver is via the portal vein, which is formed from the superior mesenteric and splenic veins and so drains the intestinal tract. The hepatic artery supplies oxygen. The organ is made up of hexagonal lobules of cells. Rows of hepatocytes radiate from the central hepatic vein and are separated by sinusoidal spaces along the walls of which are interspersed hepatic macrophages, the Kupffer Cells. These cells are part of the reticuloendothelial system and are phagocytic and so have an important detoxifying function.
At the corners of each lobule are the portal tracts that contain branches of the hepatic artery, the portal vein and the bile ducts. Blood flows from the portal tracts towards the central hepatic vein.
Liver Diseases Acute Hepatitis: Usually caused by viral infection (hep A, B, C, D, E, and Epstein Barr Virus) but also by toxins (paracetamol, alcohol etc) May be Jaundice. Bilirubin and urobilinogen detectable in the urine by dip stick.
Most cases resolve completely. Hepatic failure may develop.
Chronic Hepatitis: Persisting for more than 6 months. Causes are autoimmune hepatitis, chronic infection with hepatitis B or C and alcohol.
Plasma aminotransferase activities usually elevated but other liver function tests normal unless cirrhosis develops.
Acute Liver Failure: Can be hyperacute or sub acute. Rare condition, toxins - paracetamol and hepatitis are usual cause. Features include severe...