Which of the following substance in urine will give a positive reaction with Benedict test?

RML Lucknow - 2021

Biochemistry & Nutrition

Easy

Appeared in: RML Lucknow - 2021

Explanation

Benedict's test is specifically designed to detect the presence of reducing sugars in a sample.
Glucose is a monosaccharide and a primary example of a reducing sugar due to its free aldehyde group.
When heated with Benedict's reagent, glucose reduces the blue cupric (Cu²⁺) ions to red-orange cuprous (Cu⁺) oxide, resulting in a characteristic color change, which signifies a positive test.
The presence of glucose in urine, known as glycosuria, is a key indicator of conditions like diabetes mellitus.

Option A: Acetone is a ketone body, not a reducing sugar. It lacks the chemical structure required to react with Benedict's reagent.
Option C: Bile salts are derivatives of cholesterol and do not have reducing properties. They will not cause a color change in Benedict's test.
Option D: Albumin is a protein and does not act as a reducing agent in the context of the Benedict's test.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Urine analysis and biochemical tests for abnormal constituents as background academic context rather than a clinical decision trigger.
Nurses frequently perform urine dipstick tests at the bedside, which are modern, rapid versions of these classic chemical tests, to screen for conditions like diabetes mellitus, kidney disease, and liver problems.
A positive test for glucose in urine (glycosuria) is a critical finding that requires the nurse to report to the physician, monitor the patient's blood glucose levels, and anticipate further diagnostic tests like fasting blood sugar or HbA1c.
What if? If a patient taking high doses of Vitamin C (ascorbic acid) has a positive Benedict's test, the result could be a false positive. Ascorbic acid is also a reducing substance and can interfere with the test. A more specific glucose oxidase strip test should be used to confirm the presence of glucose.

How to Approach the Question

First, identify the key term in the question, which is 'Benedict test'.
Recall the primary purpose of the Benedict test from your knowledge of clinical biochemistry. It is used to detect reducing sugars.
Analyze each option to determine its chemical classification.
Option A, Acetone, is a ketone. Option C, Bile salt, is a steroid derivative. Option D, Albumin, is a protein.
Recognize that Option B, Glucose, is a monosaccharide, which is a type of reducing sugar.
Conclude that glucose is the only substance among the options that will give a positive reaction with the Benedict test.

Concept Tested & Keywords

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