**Question:** Microcytic hypochromic RBC is/are seen in all except -

A. Iron deficiency anemia
B. Sickle cell anemia
C. Polycythemia vera
D. Thalassemia

**Core Concept:** Microcytic hypochromic red blood cells (RBC) are characterized by small and low hemoglobin content. These cells are typically seen in conditions where the production or survival of RBC is impaired.

**Why the Correct Answer is Right:** Option C, Polycythemia vera, is a disorder where the body produces excess RBCs due to increased production of erythropoietin (EPO), a hormone regulating RBC production. In this condition, the cell size and hemoglobin content remain normal.

**Why Each Wrong Option is Incorrect:**

A. Iron deficiency anemia: Iron deficiency leads to impaired RBC production, resulting in microcytic hypochromic RBCs.
B. Sickle cell anemia: This condition involves abnormal hemoglobin (Hb) production, causing RBC deformation and not affecting size and hemoglobin content.
D. Thalassemia: Thalassemia is a group of inherited blood disorders characterized by abnormal Hb production, leading to reduced RBC size and hemoglobin content.

**Clinical Pearl:** The distinction between microcytic hypochromic RBCs in various conditions is crucial for accurate diagnosis and appropriate management. Assessing RBC size and hemoglobin content can provide valuable information regarding iron deficiency, hemoglobinopathies, and other hematological disorders.

**Correct Answer:** C. Polycythemia vera

**Explanation:** Polycythemia vera is characterized by excess RBC production due to increased EPO levels, resulting in normal-sized and hemoglobin content RBCs. In contrast, microcytic hypochromic RBCs are commonly seen in conditions like iron deficiency anemia, sickle cell anemia, and thalassemia.