A 16-month-old boy is brought to the pediatric clinic for a routine well-child evaluation. His mother mentions that he is a picky eater and refuses most solid foods. His diet consists predominantly of to ounces (approximately to ) of whole cow's milk daily, supplemented only by small amounts of crackers. He is active but occasionally appears more fatigued than his siblings did at this age. Vital signs are within normal limits. Physical examination reveals conjunctival pallor but no hepatosplenomegaly or lymphadenopathy. Laboratory studies show:
Hemoglobin:
Mean corpuscular volume (MCV):
Red cell distribution width (RDW): (normal: )
Reticulocyte count:
Which of the following is the most likely diagnosis?
- Iron deficiency anemiaAnswer
- BBeta-thalassemia minor
- CFolate deficiency
- DLead poisoning
- EPhysiologic anemia of infancy
Answer
Iron deficiency anemia
The most likely diagnosis for this patient is iron deficiency anemia. The child's presentation of pallor and fatigue, combined with a diet excessively high in cow's milk (greater than ounces per day) and poor solid food intake, is classic for this condition. Cow's milk is notoriously low in iron, and large quantities can also cause occult intestinal blood loss in toddlers. Furthermore, the laboratory findings of a microcytic anemia (low MCV) with an elevated red cell distribution width (RDW) are highly characteristic of iron deficiency anemia. The high RDW reflects anisocytosis (varying red blood cell sizes) as the iron stores become progressively depleted, which helps distinguish it from other causes of microcytosis such as thalassemia.
Step-by-Step Solution
Key Concept
Toddlers who consume excessive amounts of cow's milk (greater than ounces daily) are at high risk for iron deficiency anemia, which classically presents with a microcytic anemia and an elevated red cell distribution width (RDW).