BILIRUBIN

• Liver


  The chief metabolic organ in the body and is the largest internal organ of the body
• Liver functions


  • Synthetic function
  • Excretory function
  • Detoxification function and Drug metabolism
  • Regulatory function
  • Storage function
• Several laboratory tests are performed to assess the different functions of the liver, example is Bilirubin which is useful in assessing the conjugation and excretory function of the liver

  
• Bilirubin


  The end product of hemoglobin metabolism and the principal pigment in bile

  
• Types of bilirubin


  • Unconjugated
  • Conjugated
• Conjugation of bilirubin takes place in the presence of the enzyme uridyl diphosphate glucuronyl transferase (UDPGT)

  
• Conversion Factor


  For normal bilirubin values

  
• Van den Bergh reaction


  The determination of bilirubin involves the principle of this reaction

  
• Normal serum yields a positive Van den Bergh reaction

  
• Methods for bilirubin determination


  1. Prepare reagents

  2. Add reagents and sample to cuvette

  3. Run water blank

  4. Adjust wavelength

  5. Run sample

  6. Read absorbance and compute concentration

  
• Direct bilirubin can be measured first, then accelerator such as Methanol and Caffeine sodium benzoate is added to measure the total bilirubin. Indirect bilirubin is obtained by subtracting the value of total bilirubin from direct bilirubin

  
• Cigarette smoking has no effect on ammonia
• Bilirubin is covalently attached to albumin
• Danger of kernicterus at bilirubin levels >20 mg/dL
• Accelerator used in Jendrassik-Grof method is Caffeine Sodium Benzoate
• Deficiency of UDPGT causes Crigler Najjar syndrome

  
• Defective uptake of bilirubin causes Gilbert's syndrome

  
• Defective excretion of bilirubin causes Dubin Johnson syndrome