In a patient with pernicious anaemia the primary purpose of schilling test is to determine

NHM UP Staff Nurse-2021 Shift-1st

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Explanation

The Schilling test is a diagnostic tool specifically designed to evaluate the mechanism of vitamin B12 malabsorption.
Its primary goal is to determine if the body can effectively absorb vitamin B12 from the small intestine.
In pernicious anemia, the body lacks intrinsic factor (IF), which is necessary for B12 absorption. The test can confirm this by seeing if absorption normalizes when IF is given.
The test measures urinary excretion of a radioactive B12 dose to indirectly quantify how much was absorbed into the bloodstream.

Option A: The test does not measure dietary intake. It involves administering a known quantity of vitamin B12 to assess the body's physiological capacity for absorption.
Option C: Measuring urinary excretion is the method used in the test, but it is not the primary purpose. The excretion level is an endpoint used to infer the amount of B12 absorbed.
Option D: This option is incorrect because there is a correct answer among the choices. Option B accurately describes the primary purpose of the Schilling test.

Clinical Relevance

Nursing practice connection: Use the key finding related to Primary purpose of the Schilling test in pernicious anemia to guide bedside assessment, documentation, and the next nursing action.
The Schilling test was historically a key investigation for pernicious anemia, an autoimmune condition causing intrinsic factor deficiency.
Understanding this test helps differentiate between causes of vitamin B12 deficiency, such as pernicious anemia versus intestinal malabsorption (e.g., Crohn's disease) or dietary insufficiency.
Although now largely obsolete and replaced by tests for intrinsic factor antibodies and methylmalonic acid levels, its principle remains fundamental to understanding B12 physiology.

How to Approach the Question

First, identify the key terms in the question: 'pernicious anaemia' and 'Schilling test'.
Recall the pathophysiology of pernicious anemia: it's a condition where the stomach doesn't produce intrinsic factor, which is essential for vitamin B12 absorption.
Connect this pathophysiology to the purpose of a diagnostic test. A test for pernicious anemia would need to assess the function that is impaired, which is the absorption of B12.
Evaluate the options based on this understanding. 'Intake' relates to diet, not a physiological test. 'Excretion' is part of the test's method but not its primary clinical question.
Conclude that 'Absorption of vitamin B12' is the direct process being evaluated to diagnose the cause of the deficiency.

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