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Sample

Indications

  1. Bile salts are detected in the urine to diagnose various conditions of liver diseases (Jaundice).
  2. To diagnose obstructive jaundice.

Precaution

  1. The postprandial sample is preferred that allows a more sensitive distinction between normal abnormal results as compared to the fasting sample.  
    1. Eating will stimulate secretion.

Pathophysiology

  1. The liver assists intestinal digestion by secreting 700 to 1200 mL of bile acids per day. 
    1. Bile is an alkaline, bitter taste, the yellowish-green fluid. Bile salt contains:
      1. Conjugated bile acids.
      2. Cholesterol.
      3. Bilirubin.
      4. Electrolytes.
      5. Water.
  2. Bile acid is generated from an amino acid, Glycine, and Taurine.

  1. Definition of bile salts:
    1. Bile acids conjugated with taurine or glycine in the liver. Sodium or potassium conjugates of these bile acids are called bile salt.
      1. Primary bile acids are synthesized in the liver.
      2. Secondary bile acids are produced in the colon by the bacterial action.
    2. Bile salts are formed when an acid is neutralized by a base.
      1. Bile salt consists of:
        1. Sodium glycocholate.
        2. Sodium taurocholate.
        3. Potassium and calcium bile salts are also common.
      2. Bile salts are needed for:
        1. Facilitate fat absorption.
        2. Intestinal emulsification.
        3. Most of the bile salt is actively absorbed in the terminal ileum and return to the liver through the portal circulation for resecretion.
        4. The recycling of bile salts is termed the enterohepatic circulation.
  2. Bile salts are made in the liver from cholesterol and these help in the fat absorption. They make them more soluble.

  1. Bile salts appear in the urine when there is an obstruction to the biliary tract and that will leads to an increase in the bile acids in the blood.
  2. Bile salts are positive in urine in other liver diseases.
  3. Cholestasis, retention of bile and bile salts leads to Itching (Pruritus).
    1. The biliary obstruction prevents the bile salts from entering the duodenum leads to their accumulation in the blood.
    2. Serum bile salts may increase in liver diseases.
  4. The level of bile salts correlates with itching.
  5. This cholestatic itching may be seen in:
    1. Primary biliary cirrhosis.
    2. Primary sclerosing cholangitis.
    3. Intrahepatic cholestasis of pregnancy.
    4. Hereditary cholestatic syndrome.
  6. In the bile, deficiency of the bile salt allows cholesterol to precipitates as gall stones.

Normal

Procedure to detect bile salts in the urine:

  1. Bile salts can be quantified by:
    1. Spectrophotometry.
    2. Chromatography.
    3. Radioimmunoassay.
  2. Bile salts reduce the surface tension of liquids.
    1. On this principle, HAY’s test is done.
      1. Sulfur powder is sprinkled over the surface of urine and it sinks if bile salts are present.
      2. Sulfur will remain on the surface when bile salts are absent.

Positive bile salt test is seen in:

  1. Obstructive jaundice.
  2. Liver diseases with the appearance of jaundice.

 


Possible References Used

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