A 38-year-old woman with chronic menorrhagia presents with microcytic hypochromic anemia. Regarding the morphological and biochemical features of iron deficiency anemia, all of the following are true EXCEPT:

Explanation

## Analysis of Iron Deficiency Anemia — Morphological and Biochemical Features ### Correct Answer Explanation **Key Point:** In iron deficiency anemia, the M:E (myeloid-to-erythroid) ratio is **decreased**, not increased. The bone marrow shows erythroid hyperplasia with a shift toward increased erythropoiesis, resulting in a **low M:E ratio** (normally 3:1; in IDA it may be 1:1 or lower). ### Why Each Correct Option Is True | Feature | Finding | Explanation | |---------|---------|-------------| | **Serum ferritin** | Decreased (<15 μg/L) | Most sensitive marker for iron depletion; unaffected by inflammation in early stages | | **RDW** | Elevated (>15%) | Reflects wide variation in RBC size due to unequal hemoglobinization | | **TIBC & transferrin saturation** | ↑ TIBC, ↓ saturation | Iron-binding proteins increase as body attempts to maximize iron uptake | ### Bone Marrow Findings in IDA **High-Yield:** The bone marrow in iron deficiency anemia shows: - **Erythroid hyperplasia** (compensatory response to anemia) - **Decreased M:E ratio** (shift toward erythroid predominance) - **Absence of iron stores** on Prussian blue stain (diagnostic) - **Micronormoblasts** (small erythroid precursors reflecting iron limitation) **Clinical Pearl:** The M:E ratio inversion (erythroid predominance) is a hallmark of IDA and distinguishes it from other causes of microcytic anemia where myeloid predominance may occur. ### Mnemonic for IDA Lab Pattern **"TIBC Up, Iron Down"** — In IDA, transferrin and TIBC rise while serum iron, ferritin, and saturation fall.