Rosh Pediatrics Practice Exam

What lab value is consistent with a diagnosis of iron deficiency anemia in a 14-year-old girl following a strict vegan diet?

1. AD-dimer of 600 ng/mL

2. BFerritin of 75 µg/L

3. CRed blood cell distribution width of 7%

4. DTotal iron-binding capacity of 470 µg/dL

The correct answer is: DTotal iron-binding capacity of 470 µg/dL

In the context of iron deficiency anemia, particularly for a 14-year-old girl on a strict vegan diet, the total iron-binding capacity (TIBC) provides significant insight. In iron deficiency anemia, the body attempts to increase the absorption of iron to compensate for its deficiency, which often leads to an elevation in TIBC. A TIBC value of 470 µg/dL suggests a poor iron status because it is indicative of the body's attempt to maximize the use of limited iron resources. While other lab values could provide relevant information about anemia, such as ferritin levels or red blood cell distribution width, they would not be consistent with iron deficiency anemia in this scenario. For example, ferritin is typically low in iron deficiency anemia, and a high ferritin value like 75 µg/L would indicate adequate iron stores, which contradicts a diagnosis of iron deficiency. The red blood cell distribution width (RDW) also usually increases in iron deficiency anemia, and a 7% RDW indicates a low variability in red blood cell sizes, which is not typical for iron deficiency. Therefore, a TIBC of 470 µg/dL aligns well with the expected laboratory findings in iron deficiency anemia for someone in this situation, showcasing the