Hematologic Disorders and Anemia Q 50

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The primary purpose of the Schilling test is to measure the client’s ability to:

  

     A. Store vitamin B12

     B. Digest vitamin B12

     C. Absorb vitamin B12

     D. Produce vitamin B12

    

    

Correct Answer: C. Absorb vitamin B12

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Pernicious anemia is caused by the body’s inability to absorb vitamin B12. This results in a lack of intrinsic factor in the gastric juices. Schilling’s test helps diagnose pernicious anemia by determining the client’s ability to absorb vitamin B12. Patients presenting with signs and symptoms of cobalamin used to undergo this test. The most common features of vitamin-B12 deficiency include severe macrocytic anemia and variable neurologic abnormalities such as shuffling gait, with no improvement observed upon the administration of folic acid.

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Option A: In the systemic circulation, cobalamin binds with transporter protein termed transcobalamin II (TCII) and enters into the tissue with the receptor of transcobalamin II. Cobalamin has many cellular effects with the greatest impact on new blood cell generation and neurological function. At the cellular level, cobalamin acts as a cofactor of two enzymatic reactions that involve methionine synthase and methyl- malonyl-co A mutase.

Option B: If cobalamin is not present in sufficient amounts, megaloblastic anemia occurs by inhibition of DNA synthesis due to the folate trap. Cobalamin (vitamin B12) in the form of adenosylcobalamin acts as a cofactor for enzyme methyl- malonyl-co A mutase, which converts methyl malonyl CoA to succinyl CoA. Through this reaction, it helps to metabolize odd chain fatty acids and branched chain amino acids.

Option D: Vitamin B12 is naturally found in animal products, including fish, meat, poultry, eggs, milk, and milk products. Vitamin B12 is generally not present in plant foods, but fortified breakfast cereals are a readily available source of vitamin B12 with high bioavailability for vegetarians.

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