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 assess the body's ability to absorb vitamin B12 from the gastrointestinal tract.
It helps differentiate between different causes of B12 deficiency, such as dietary lack, pernicious anemia (lack of intrinsic factor), or intestinal malabsorption.
The test involves giving a patient radioactive vitamin B12 orally and then measuring how much is excreted in the urine over 24 hours.
A low level of excreted radioactive B12 indicates that the vitamin was not properly absorbed from the gut.

Option A: The test does not measure digestion. Vitamin B12 is released from food by acid and pepsin, but the test assesses the subsequent absorption process in the ileum.
Option B: Distribution refers to the transport of B12 in the bloodstream to various tissues after it has been absorbed. The Schilling test evaluates the initial step of getting B12 into the body, not where it goes afterward.
Option D: Although urinary excretion is measured, it is only a means to an end. The goal is not to test kidney function but to use the amount excreted as an indirect indicator of how much was absorbed from the gut. If absorption is poor, little will be available to be excreted.

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 its use of radioactivity, was a cornerstone in diagnosing pernicious anemia. Understanding its principle is key to understanding B12 metabolism.
A nurse's role is critical in ensuring the accuracy of the test, which involves meticulous 24-hour urine collection and patient education about the procedure.
What if? If a patient has had a gastrectomy (removal of the stomach), they would fail Stage I of the Schilling test because their stomach no longer produces intrinsic factor. Their results would mimic pernicious anemia.

How to Approach the Question

First, identify the core subject of the question: the 'Schilling test'.
Recall or deduce the primary function of this specific diagnostic test. The name itself doesn't give a clue, so this relies on factual recall.
Analyze the options provided: digestion, distribution, absorption, and excretion. These represent different physiological processes.
Connect the function of the Schilling test to these processes. The test involves giving an oral substance (B12) and measuring its appearance in the urine to see how much entered the body from the gut.
This process of moving a substance from the gut into the bloodstream is the definition of 'absorption'.
Eliminate the other options. 'Excretion' is part of the method but not the purpose. 'Digestion' and 'distribution' are different, distinct processes in nutrient handling.

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

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E6 Pharmacology Katzung 16e p. 934-936

E6 PATHOLOGY QUICK REVIEWBased on Harsh Mohan Textbook of PATHOLOGY pp. 106-108, 105-107