Secondary bile acid is?

Appeared in: DSSSB - 29 August 2019 (Shift-1)

Explanation

Lithocholic acid is classified as a secondary bile acid.
It is not synthesized directly in the liver but is formed in the colon.
Intestinal bacteria metabolize the primary bile acid, chenodeoxycholic acid, to produce lithocholic acid.
This conversion process is known as 7-alpha-dehydroxylation.

Option A: Taurocholate is a conjugated bile acid, also known as a bile salt.
Option C: Cholic acid is a primary bile acid, not a secondary one.
Option D: Chenodeoxycholic acid is also a primary bile acid.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of bile acids (primary vs. secondary) as background academic context rather than a clinical decision trigger.
Bile acids are crucial for emulsifying dietary fats, which is the first step in their digestion and absorption. Without adequate bile acids, fat malabsorption (steatorrhea) and deficiencies in fat-soluble vitamins (A, D, E, K) can occur.
The entire pool of bile acids circulates between the liver and intestine 6-10 times a day (enterohepatic circulation). Disruption of this circulation, for example, due to ileal resection, can lead to a significant loss of bile acids.
An imbalance in the ratio of cholesterol to bile acids and phospholipids in bile can lead to the supersaturation of cholesterol, resulting in the formation of cholesterol gallstones.

How to Approach the Question

First, identify the core concept of the question, which is the classification of bile acids.
Recall or determine the definition of primary and secondary bile acids. Primary acids are made in the liver from cholesterol. Secondary acids are made in the intestine by bacteria acting on primary acids.
Evaluate each option based on these definitions.
Option A, Taurocholate, ends in '-ate' and contains 'tauro-', suggesting it's a conjugated salt with taurine, not a secondary acid.
Options C (Cholic acid) and D (Chenodeoxycholic acid) are the two main primary bile acids.
By elimination, Option B (Lithocholic acid) must be the secondary bile acid. Confirm this by recalling that it's formed from chenodeoxycholic acid in the colon.

Concept Tested & Keywords

Q1NxHZY2kbD5ZK1BDjEP-L

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 220-222

E6 Medicine Harrison 22e Part 2 p. 631-633

Practise the full DSSSB - 29 August 2019 (Shift-1)

Attempt every question from this paper in a timed mock, then review the full solution for each one.