Bile is a yellow-green fluid that contains water and organic molecules such as cholesterol, bile acids, and bilirubin. In humans, the two main function of bile are the digestion and absorption of fats and the elimination of bile salts from the body by secretion into bile. Adult humans produce around 400 to 800 ml of bile daily. Bilirubin is detected in urine in certain pathological conditions only. Bilirubin is not found in urine. It is present in urine during jaundice or because of liver damage
The Foaming test for bile salts and bile pigments is another inexpensive and easy specific test used for the qualitative detection of bile salts and bile pigments in urine.
So many other inexpensive and easy tests do exist for the qualitative detection bile salts and bile pigments. Like the Gmelin’s test for bile pigments and Hay’s test for bile salts.
Principle of the test method
Bile is produced by the liver. The formation of bile salts starts with the breakdown of red blood cells. The iron-free portion of heme is converted to biliverdin, a green pigment, and then into bilirubin, a yellow orange pigment. In the liver, bilirubin are excreted in the bile as bile pigments, which passes into the small intestine and then into the large intestine. It is present in urine during jaundice or because of liver damage.
The Vigorous shaking on urine separates these pigments, to detect foaming for positive samples.
Foaming test procedure
- Add 5 ml of urine in a test tube.
- Shake the tube vigorously and then examine for foaming.
- The Appearance of distinct yellow or brownish foam will qualitatively indicate the presence of both bile salts and bile pigments.
- If No foam produce, Bile sale and bile pigment Negative.
- Normally bile pigments are absent in the normal urine.
It is advisable to confirm this test with other quantitative means using spectrophotometer, colorimeter and other liver function test before concluding