Q66.Pernicious anemia is a result of
A. Deficiency of Vitamin B₂
B. Deficiency of Vitamin C
C. Blockage of Vitamin B₁₂ absorption
D. Blockage of Vitamin A absorption
E. Lack of proteins in diet
Choose the correct answer from the options given below :
(1) A, B, C and E Only
(2) C Only
(3) B, C and D Only
(4) D and E Only
The correct answer is option (2): C Only.
Pernicious Anemia Cause
Pernicious anemia specifically results from blockage of vitamin B12 absorption in the ileum due to insufficient intrinsic factor (IF), a glycoprotein secreted by gastric parietal cells that’s autoimmunely destroyed, preventing B12 binding and uptake despite adequate dietary intake. This leads to megaloblastic anemia with large, immature RBCs, unlike simple dietary deficiencies resolvable by supplements alone—pernicious cases require lifelong B12 injections.
Option Analysis
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Option (1) A, B, C and E Only: Incorrectly includes Vitamin B2 (causes angular cheilitis, normocytic anemia), Vitamin C (scurvy, no RBC morphology change), and protein lack (kwashiorkor, hypoalbuminemia); only C matches.
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Option (2) C Only: Precisely correct—IF deficiency uniquely defines pernicious anemia per hematology standards.
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Option (3) B, C and D Only: Wrongly adds Vitamin C (microcytic bleeding) and Vitamin A blockage (xerophthalmia, no anemia).
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Option (4) D and E Only: Misses B12 link; Vitamin A issues cause night blindness, protein deficiency causes marasmus edema.
Introduction: Pernicious Anemia Is a Result of Blockage of Vitamin B12 Absorption
NEET biology frequently tests pernicious anemia causes, pinpointing if it’s “blockage of vitamin B12 absorption” among vitamin deficiencies. Confirming pernicious anemia is a result of blockage of vitamin B12 absorption via intrinsic factor loss secures exam points. This details option (2) C only, pathology, and prep strategies.
Core Cause: Vitamin B12 Malabsorption
Autoimmune gastritis targets parietal cells, slashing IF production essential for B12 ileal absorption. Symptoms emerge after years: fatigue, paresthesia, atrophic glossitis, hypersegmented neutrophils. Diagnosis: low B12, anti-IF antibodies, Schilling test.
Eliminating Other Options
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A (B2): Riboflavinosis → oral lesions.
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B (C): Scurvy → petechiae.
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C: Pernicious hallmark—confirmed by gastric biopsy atrophy.
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D (A): Keratinization.
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E: Muscle wasting.
NEET Winner: Option (2) C Only
Specific to B12 absorption defect; distinguishes from folate deficiency (no neuro effects). Treatment: IM cyanocobalamin monthly.
NEET Prep: Anemia Deficiency Quick Guide
Mnemonic: “Pernicious = B12’s Pernicious IF Block.”
