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Bile Salts in the Urine

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Bile Salts: An Introduction

Bile salts are made of four types of acids. Bile salts help in the digestion and absorption of food.

The presence of bile salts in urine is an indicator of liver problems.

What is Bile and its Composition?

Bile is a greenish yellowish liquid that is made and released by the liver but stored by the gallbladder which is a small pouch located below the liver.

Bile mainly consists of water in which many constituents such as bile salts, bilirubin, phospholipids, cholesterol, enzymes, and vitamins are dissolved.

There are five main constituents of bile:

What are Bile Salts?

Bile salts are the chemicals that enable the body to excrete harmful chemicals and cholesterol. Bile salts are also known as biological detergents.

The function of bile salts is to solubilize the ingested fat and fat-soluble vitamins and other chemical compounds.

What are Bile Pigments?

Bile pigments are the component that generates endogenously during the breakdown of hemoglobin. Bilirubin and biliverdin are two bile pigments.

What is the Composition of Bile Salts?

  • Bile salts are synthesized in the liver of mammals.

  • Bile salts are made of salts of four different kinds of free bile acids. These four acids are cholic, deoxycholic, chenodeoxycholic, and lithocholic acids. These acids combine with amino acids such as taurine and glycine to create more complex acids and salts.

  • Bile salts are synthesized in the liver or maybe from cholesterol, after their synthesis they pass into the bloodstream.

Bile Salt Test

  • This test is done to find the presence of bile salts/pigments in urine.

  • Bile salts/pigments present in urine in diseased conditions. This test can be done to find certain diseases such as jaundice and other liver diseases.

  • To detect the presence of bile salts in the urine, a smith's test is done.

  • Gmelin's test is done to find the presence of bile pigments in urine.

Smith's test

Article required

  • Smith's reagent

  • Dropper

  • Test tube

  • Measuring cylinder

  • Urine sample


  1. Take a sterile and dried test tube

  2. Using a measuring cylinder add 1 ml of smith's reagent into the test tube

  3. Take the urine sample in the dropper and hold the test tube in an inclined position and slowly add urine to the sides or walls of the test tube.

  4. Observe the change and note the color of the solution

Observation and Conclusion

If the green color ring is formed at the intersection of both layers, this indicates the presence of bile salts in the urine.

smith's test

Smith's Test

Gmelin's Test

Articles Required

  • Test tube

  • Measuring cylinder

  • Urine sample

  • Gmelin's reagent (nitric acid)


  1. Take 3ml of concentrated gmelin's reagent in a test tube

  2. Add 3ml of urine sample carefully along the side of the test tube so that two liquids do not mix

  3. Now observe the solution

Observations and Conclusion

Bile pigments will be present in urine if a display of colors from yellow, red, blue, and green is noted at the point of contact of the two liquids.

Gmelin's Test

Gmelin's Test

Interesting Facts

  • Bile is the greenish or somewhat yellowish color

  • Bile pigments make the green color of bile

  • The liver produces 0.5-1 liter of bile every day

  • Gallbladder concentrates that bile by ten folds and stores 30-50 ml of bile

  • A person can survive without a gallbladder

Important Questions

1. How are bile salts detected in urine?

Ans: Various tests are available to find the presence of bile salts in urine.

2. What is the difference between bile salts and bile pigments?

Ans: There are so many differences between bile salts and bile pigments. The most important difference is bile salts are derivatives of cholesterol whereas bile pigments are made up of the breakdown product of hemoglobin.

3. What diseases are associated with bile pigment abnormalities?

Ans: The main disease is jaundice which is due to abnormalities of bile pigments. Excess accumulation of pigments in the bloodstream is the main cause of jaundice.

Practice Questions

  1. What causes bile pigmentation?

  2. What happens if bile pigment is negative?

  3. What are the three bile pigments?

  4. What are the symptoms of bile deficiency?

Key Features

  • Our liver releases bile juice, bile pigments, and bile salts. Bile juice stored in the gallbladder

  • Normally bile salts and pigments do not excrete in urine.

  • If bile salts or pigments are present in the urine, then it is an indication of a certain liver disease

  • Various tests are used to find the presence of bile in urine but the most important tests are smith's test and gmelin's test

  • Smith's test is used to find the presence of bile salts in urine whereas gmelin's test is conducted for bile pigments in urine

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FAQs on Bile Salts in the Urine

1. What are four warning signs of a damaged liver?

There are various signs of damaged liver

  • Swelling of lower legs due to fluid retention 

  • Dark-colored urine due to the presence of bile salts and bile pigments in urine.

  • Pain and distension of the abdomen due to liver damage

  • Pale colored stool

  • Nausea and vomiting

  • Loss of appetite may lead to weight loss

  • Bloody stool

  • Tendency to bruise easily

  • Swelling of the liver may lead to discomfort in the upper right side of the abdomen

  • Portal hypotension maybe there

  • Jaundice

2. What are the functions of bile salts?

There are various functions of bile salts:

It helps in the breakdown of fat and its digestion. It also absorbs important vitamins. Bile salts also help in neutralizing the acidic pH of the chyme. It is the primary component of bile juice.

Bile acid also activates lipase which helps in the digestion of fat.

Provide support to those without a gallbladder. It also controls blood sugar levels. It helps in the digestion of fat-soluble vitamins. It also helps in improving the metabolism

3. Explain the bile juice.

Bile juice is released from the liver and stored in the gallbladder. The composition of bile juice is mostly water. Almost 95% of bile juice is composed of water. Other than this bile pigments, bile salts, phospholipid, cholesterol, amino acid, enzymes, vitamins, and heavy metals are also present in bile juice. Bile juice is greenish yellow. It aids in digestion. It does not contain any enzymes. Bile is most important for the digestion of lipids

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