A 45yr old presents with paresthesia Hb 6.8 g1dL Peripheral smear shows macrocytes and neutrophils with hypersegmented nuclei Endoscopy reveals atopic gastritis Which of the following defficiency is more likely ?
**Core Concept**
The patient's presentation of paresthesia, macrocytic anemia, hypersegmented neutrophils, and atrophic gastritis suggests a deficiency in vitamin B12, which is essential for the synthesis of myelin and the maintenance of the nervous system.
**Why the Correct Answer is Right**
Vitamin B12 deficiency leads to a decrease in the production of myelin, resulting in nerve damage and paresthesia. The macrocytic anemia is due to impaired DNA synthesis in red blood cell precursors, causing an increase in the size of red blood cells (macrocytes). Hypersegmented neutrophils are a characteristic feature of megaloblastic anemia, which is caused by impaired DNA synthesis. Atrophic gastritis leads to a decrease in the production of intrinsic factor, a protein necessary for the absorption of vitamin B12.
**Why Each Wrong Option is Incorrect**
**Option A:** While folate deficiency can also cause megaloblastic anemia, it does not typically cause atrophic gastritis or paresthesia. Folate deficiency is more commonly associated with dietary deficiencies or increased requirements during pregnancy.
**Option B:** Iron deficiency anemia is characterized by microcytic hypochromic red blood cells, not macrocytes. It also does not typically cause atrophic gastritis or paresthesia.
**Option C:** Vitamin C deficiency (scurvy) causes a range of symptoms including fatigue, malaise, and connective tissue weakness, but it does not typically cause macrocytic anemia or atrophic gastritis.
**Clinical Pearl / High-Yield Fact**
When evaluating a patient with macrocytic anemia and atrophic gastritis, always consider vitamin B12 deficiency as a primary cause. This is because atrophic gastritis can lead to a decrease in intrinsic factor production, impairing vitamin B12 absorption.
**Correct Answer:** D. Vitamin B12 deficiency.