Liver Function and Porphyrin Formation

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Liver Function and Porphyrin Formation
2013-05-05 20:28:21
Liver Function Bilirubin Urobilinogen Porphyrins

Liver Function, Bilirubin, Urobilinogen, Porphyrins
Show Answers:

  1. What all does the liver synthesize?
    • Proteins
    • Coagulation factors
    • Ammonia
    • Carbs
    • Fat
    • Ketones
    • Vit A
    • Enzymes
    • and so on...
  2. What is the principal pigment in bile that is derived from hemoglobin breakdown?
  3. How does bilirubin get transported to the liver?
    • Bilirubin forms a complex with albumin for transport to the liver
    • In this form, bilirubin is unconjugated and NOT water soluble
  4. When is bilirubin conjugated?
    • Conjugated in the hepatocyte endoplasmic reticulum with glucuronic acid to form bilirubin diglucuronide
    • The reaction is catalyzed by uridine diphosphate (UDP) glycuronyltransferase
  5. Which form of bilirubin is water soluble, unconjugated or conjugated?
    Conjugated is water soluble
  6. What has an orange-brown pigment that gives stool its characteristic color?
  7. What does the liver secrete to assist in digestion?
  8. Where is bile stored?
  9. What organ is the primary site in the body for synthesis of waste products, conjugation of hormones, and bilirubin to water-soluble forms, and conversion of drugs to metabolites for excretion in urine or stool?
  10. What clinical condition occurs when there is excessive erythrocyte destruction (as hemolytic anemias, spherocytosis, toxic conditions, hemolytic disease of the newborn caused by Rh or ABO incompatibility)?
    Prehepatic jaundice
  11. What clinical condition occurs when the liver cells malfunction and cannot take up, conjugate, or secrete bilirubin?
    Hepatic jaundice
  12. What clinical condition:
    Defect in the ability of hepatocytes to take up bilirubin
    Due to transport problem of bilirubin from the sinusoidal membrane to the mircrosomal region
    Gilbert syndrome
  13. What clinical condition is a partial or complete deficiency of UDP-glycuronyltransferase?
    Crigler-Najjar disease
  14. What clinical condition is characterized by a defective liver cell excretion of bilirubin due to impaired transport in the hepatocyte of conjugated bilirubin from microsomoal region to the bile canaliculi?
    Dubin-Johnson syndrome
  15. What clinical condition is characterized by a level of UDP-glycuronyltransferase is low at birth?
    Neonatal physiological jaundice
  16. What clinical condition may be caused by hepatocyte injury such as cirrhosis, bile duct injury (like Rotor syndrom or neoplasms)?
    Intrahepatic jaundice
  17. What clinical condition occurs when and obstruction blocks the flow of bile into the intestines?
    • Posthepatic jaundice
    • (also called extrahepatic cholestasis)
  18. What disorder is a result of chronic scarring of liver tissue turning it into nodules?
  19. What is the tumor that is the primary cancer of the liver?
    Hepatocellular carcinoma or hepatoma
  20. What tumor arises from other cancerous tissue where the primary site was of lung, pancreas, gastrointestinal tract or ovary origin?
    Metastatic liver tumors
  21. What syndrome has an unknown cause but include symptoms of encephalopathy, neurologic abnormalities including seizures or coma, and abnormal liver function tests due to hepatic destruction?
    Reyes syndrome
  22. What lab tests are markers for hepatocellular necrosis?
    • ALT: Most specific for hepatocyte injury
    • AST: Less specific than ALT
    • LD: Least specific
  23. What lab tests are markers that reflect cholestasis?
    • ALP
    • GGT
  24. What other lab tests are used to assess liver disorders?
    • Bilirubin (total, direct (conjugated), and indirect (unconjugated))
    • Albumin
    • Ammonia
    • AFP
  25. What test methodologies are used to measure bilirubin?
    • Jendrassik-Grof total bilirubin test
    • Direct spectrophotometric
  26. What are the reference ranges for bilirubin?
    • Infants Total Bilirubin: 2-6 mg/dL
    • Adults Total Bilirubin: 0.2-1.0 mg/dL
    • Indirect Bilirubin: 0.2-0.8 mg/dL
    • Direct Bilirubin: 0.0-0.2 mg/dL
  27. What causes a decrease in urobilinogen?
    Posthepatic obstruction
  28. What causes an increase in urine urobilinogen?
    • Hemolytic disease
    • Hepatocellular disease (Hepatitis)
  29. What is the reference range of urine urobilinogen?
    0.1-1.0 Ehrlich units/2 hr
  30. Deficiency of any of the specific enzymes that catalyze the formation of the prophyrinogens results in _________
    Results in excess formation of the corresponding porphyrin
  31. Name the clinically significant porphyrins
    • Urophorphyrin
    • Coproporphyrin
    • Protoporphyrin
  32. Name the types of porphyrias
    • Plumboporphyria
    • Acute intermittent porphyria
    • Congenital erythropoietic porphyria
    • Porphyria cutanea tarda
    • Hepatoerythropoietic porphyria
    • Herediatry coproporphyria
    • Variegate porphyria
    • Erythropoietic porphyria
  33. What is the term for overproduction or accumulation of porphyrins and precursors in the bone marrow?
    Erythropoietic porphyrias
  34. What is the term for overproduction or accumulation of porphyrins and precursors in the liver?
    Hepatic porphyrias
  35. What test methodology is used to measure porphyrins?
    • Watson-Schwartz test
    • (forms red condensation product with porphobilinogen)