AIIMS Rishikesh NO -…: Schilling test is used to diagnose?

AIIMS Rishikesh NO - 2019

Medical & Surgical Nursing

Easy

Appeared in: AIIMS Rishikesh NO - 2019

Explanation

The Schilling test is specifically designed to evaluate the body's ability to absorb vitamin B12 from the small intestine.
It helps determine the underlying cause of vitamin B12 deficiency, particularly malabsorption issues.
By measuring the amount of orally ingested radioactive B12 that is excreted in the urine, clinicians can infer how much was absorbed into the bloodstream.
The test is crucial for diagnosing pernicious anemia, a condition caused by the lack of intrinsic factor, which is necessary for B12 absorption.

Option A: Digestion refers to the breakdown of food into smaller components. The Schilling test uses pure vitamin B12, bypassing the digestive process, to directly assess its uptake (absorption).
Option B: Distribution describes the transport of a substance throughout the body after it enters the circulation. The Schilling test measures how much B12 gets into the circulation, not where it goes afterward.
Option D: Although urinary excretion is the method of measurement, the test's purpose is not to evaluate the kidneys' ability to excrete B12. Instead, excretion is used as an indirect indicator of how much B12 was absorbed from the gut in the first place.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Diagnostic purpose of the Schilling test for Vitamin B12 deficiency as background academic context rather than a clinical decision trigger.
The Schilling test, though now rarely used due to radioactivity and the availability of other tests (like anti-intrinsic factor antibodies), was historically vital for diagnosing pernicious anemia, a lifelong condition requiring B12 replacement therapy.
A nurse's role is critical in ensuring the accuracy of the test, which involves providing clear patient instructions, ensuring the patient is fasting, and meticulously collecting all urine for 24 hours.
What if? If a patient with suspected B12 deficiency has chronic kidney disease, the Schilling test would be unreliable. Impaired renal function would decrease the excretion of radioactive B12, falsely suggesting malabsorption. In this case, direct measurement of serum methylmalonic acid and homocysteine levels would be a more appropriate diagnostic approach.

How to Approach the Question

First, identify the core subject of the question, which is the 'Schilling test'.
Recall or deduce the primary medical purpose of this specific test. The name itself doesn't give many clues, so this relies on factual knowledge.
Analyze the options provided: digestion, distribution, absorption, and excretion. These represent different stages of how the body processes a substance.
Connect the function of the Schilling test to one of these physiological processes. The test involves giving oral B12 and measuring it in the urine to see how much got into the body system from the gut.
This process of uptake from the gut into the bloodstream is the definition of 'absorption'. Therefore, select the option that matches this function.

Concept Tested & Keywords

Concept Tested: Diagnostic purpose of the Schilling test for Vitamin B12 deficiency.
Stem keywords: Schilling test, diagnose
Lead-in keywords: BEST, MOST RELEVANT CLUE
Negative lead-in flag: false