An 18-year-old woman has a low hemoglobin value of 10.5 g/dL on routine CBC testing. The red cells are microcytic, but the WBC and platelet counts are normal. She has an adequate intake of iron-containing foods, her menstrual flow is normal, and there is no other history of blood loss. Her physical examination is completely normal, and iron studies reveal a normal ferritin level. She states that other members in her family have also been told they are anemic and given a diagnosis of alpha-thalassemia. Formation of which of the following hemoglobin’s is increased in alpha-thalassemia?
An 18-year-old woman has a low hemoglobin value of 10.5 g/dL on routine CBC testing. The red cells are microcytic, but the WBC and platelet counts are normal. She has an adequate intake of iron-containing foods, her menstrual flow is normal, and there is no other history of blood loss. Her physical examination is completely normal, and iron studies reveal a normal ferritin level. She states that other members in her family have also been told they are anemic and given a diagnosis of alpha-thalassemia. Formation of which of the following hemoglobin’s is increased in alpha-thalassemia?
💡 Explanation
**Core Concept**
The question tests the understanding of **alpha-thalassemia**, a genetic disorder affecting the production of the alpha-globin chains of **hemoglobin**. Alpha-thalassemia is characterized by a reduction in the production of alpha-globin chains, leading to a relative excess of beta-globin chains.
**Why the Correct Answer is Right**
In **alpha-thalassemia**, the decrease in alpha-globin chain production leads to a compensatory increase in the formation of **hemoglobin A2** (alpha2delta2) and **hemoglobin F** (alpha2gamma2) is not the primary increase, but **hemoglobin Barts** (gamma4) and **hemoglobin H** (beta4) are also formed due to the excess of gamma and beta chains. However, **hemoglobin H** is specifically notable as it is a pathognomonic marker for alpha-thalassemia, formed by the tetramerization of excess beta-globin chains.
**Why Each Wrong Option is Incorrect**
**Option A:** This option might refer to an increase in **hemoglobin A**, which is the normal adult hemoglobin and would not be increased in alpha-thalassemia.
**Option B:** This might refer to **hemoglobin F**, which, while it can be elevated in some cases of alpha-thalassemia, is not the most directly related to the pathophysiology described.
**Option D:** This option might refer to other abnormal hemoglobins, but without specific reference, it's less directly related to the primary issue in alpha-thalassemia.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that alpha-thalassemia can present with microcytic anemia, similar to iron deficiency anemia, but with a normal **ferritin level**, which helps differentiate it from iron deficiency. The presence of **hemoglobin H** is particularly diagnostic of alpha-thalassemia.
**Correct Answer:** C. Hemoglobin H
✓ Correct Answer: A. H
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