A 29-year-old woman was found to have a hemoglobin of 7.8 g/dl. with a reticulocyte count of 0.8%. The peripheral blood smear showed microcytic hypochromic anemia, Hemoglobin A2 and hemoglobin F levels were 2.4% and 1.3% respectively. The serum iron and the total iron binding capacity were 15 micro g/dl, and 420 micro g/dl, respectively. The most likely cause of anemia is –

**Core Concept**
The patient presents with microcytic hypochromic anemia, which is characterized by small (microcytic) and pale (hypochromic) red blood cells. This type of anemia is often associated with iron deficiency or thalassemia.

**Why the Correct Answer is Right**
The serum iron level is significantly low at 15 micro g/dl, while the total iron binding capacity (TIBC) is elevated at 420 micro g/dl. This pattern is consistent with iron deficiency anemia, where the body's iron stores are depleted, leading to a decrease in serum iron levels. The elevated TIBC is a compensatory response to the low serum iron, as the body produces more transferrin to bind and transport iron. The peripheral blood smear shows microcytic hypochromic anemia with a normal hemoglobin A2 and hemoglobin F level, which makes thalassemia less likely.

**Why Each Wrong Option is Incorrect**
**Option B:** This option is incorrect because beta-thalassemia major is typically associated with a more severe reduction in hemoglobin production, leading to a higher hemoglobin F level and a more significant increase in hemoglobin A2 level.

**Option C:** This option is incorrect because sideroblastic anemia is characterized by an elevated serum iron level, which is not consistent with the patient's laboratory results.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that in cases of microcytic hypochromic anemia, the serum iron and TIBC levels can help differentiate between iron deficiency anemia and thalassemia. A low serum iron with an elevated TIBC is characteristic of iron deficiency anemia.

**Correct Answer:** D. Iron deficiency anemia.

✓ Correct Answer: A. Iron deficiency anemia