Regarding the pathophysiology and laboratory diagnosis of iron deficiency anemia, all of the following statements are correct EXCEPT:

Explanation

## Pathophysiology and Diagnosis of Iron Deficiency Anemia ### Correct Answer Explanation **Key Point:** Target cells (codocytes) are NOT a characteristic finding in iron deficiency anemia. Target cells are seen in conditions with **decreased hemoglobin-to-cell volume ratio** such as **liver disease, thalassemia trait, and post-splenectomy**—not IDA. **High-Yield:** The peripheral smear in IDA shows: - **Microcytes** (small RBCs) - **Hypochromia** (pale central pallor, >1/3 of cell diameter) - **Pencil cells** (elliptocytes, anisopoikilocytosis) - **Occasional polychromasia** (reticulocytosis in response to anemia) ~~Target cells~~ are NOT seen in IDA; they indicate a different pathophysiology. ### Correct Statements Explained | Statement | Truth | Rationale | |-----------|-------|----------| | **Iron & heme synthesis** | ✓ Correct | Iron is the central atom in protoporphyrin IX; without it, hemoglobin cannot be synthesized | | **sTfR elevation** | ✓ Correct | sTfR ↑ in IDA and remains elevated despite inflammation; superior to ferritin for IDA diagnosis | | **DMT1 absorption** | ✓ Correct | DMT1 (also called NRAMP2) is the primary transporter for Fe²⁺ in duodenum/proximal jejunum | ### Mnemonic for Target Cells **"Target = Thin Hemoglobin Layer"** — Seen in liver disease, thalassemia trait, post-splenectomy (conditions with ↓ Hb relative to cell size). NOT in IDA.