A patient presents with fatigue, pallor, and dyspnea on exertion. Laboratory tests reveal a low hemoglobin level, decreased mean corpuscular volume (MCV), and decreased mean corpuscular hemoglobin concentration (MCHC). Which of the following conditions is most likely to cause these findings?
Correct Answer: A
Rationale: The patient's presentation with fatigue, pallor, dyspnea on exertion, low hemoglobin level, decreased MCV, and decreased MCHC are all consistent with iron deficiency anemia. Iron deficiency anemia is the most common type of anemia and occurs when there is insufficient iron available for hemoglobin production. The low hemoglobin level results in symptoms such as fatigue and pallor, while the decreased MCV and MCHC indicate microcytic and hypochromic red blood cells, respectively, which are characteristic of iron deficiency anemia. Vitamin B12 deficiency anemia and thalassemia typically present with a different pattern of laboratory findings and clinical manifestations. Sickle cell anemia is characterized by sickle-shaped red blood cells due to a genetic mutation, and the laboratory findings in sickle cell anemia are different from those seen in the patient described in this scenario.