Iron Deficiency Anemia
This 2-year-old girl has iron deficiency anemia (IDA), confirmed by the combination of severe microcytic hypochromic anemia (MCV 62 fL, MCH 18 pg/cell), low ferritin (9 g/L), and classic risk factors including excessive cow's milk intake and poor dietary iron intake.
Diagnostic Reasoning
The laboratory findings definitively point to iron deficiency anemia through multiple converging parameters:
Microcytic hypochromic pattern: MCV of 62 fL (normal 80-95 fL) and MCH of 18 pg/cell (normal 28-33 pg/cell) indicate small, pale red blood cells characteristic of inadequate hemoglobin synthesis 1
Low ferritin confirms iron deficiency: Ferritin of 9 g/L is well below the diagnostic threshold of <30 μg/L for iron deficiency in the absence of inflammation 1. This is the most powerful confirmatory test for iron deficiency 1
Elevated reticulocyte count (3%): This indicates appropriate bone marrow response attempting to compensate for the anemia, which excludes primary bone marrow disorders and is consistent with nutritional deficiency 1
Reactive thrombocytosis (480 × 10⁹/L): The elevated platelet count is a common reactive finding in iron deficiency anemia, particularly in children 2, 3
Why Other Diagnoses Are Excluded
Sickle cell disease would present with normocytic or slightly macrocytic anemia, not microcytosis, and would show sickled cells on blood smear with hemolysis markers 1.
Alpha thalassemia trait typically shows microcytosis with an elevated or normal RBC count (not low as in this case), normal or near-normal hemoglobin levels, and most importantly, normal ferritin levels 1. The severely low ferritin here excludes thalassemia.
Anemia of chronic disease (ACD) would show ferritin >100 μg/L with transferrin saturation <20% 1. The ferritin of 9 g/L definitively excludes ACD as the primary diagnosis.
Risk Factors Present in This Case
This child has classic risk factors for iron deficiency anemia in toddlers:
Excessive cow's milk intake (3 glasses daily): Cow's milk is low in iron and inhibits iron absorption while displacing iron-rich foods from the diet 2, 3
Picky eating with meat refusal: Heme iron from meat is the most bioavailable form of dietary iron 2, 3
Age 9 months to 3 years: This is the highest risk period for iron deficiency anemia in children due to rapid growth and increased iron demands 2, 3
Family history: The similar presentation in siblings suggests shared dietary patterns and possibly genetic predisposition to iron deficiency 2
Clinical Significance
The severe anemia (Hb 4 g/dL) in this toddler requires urgent attention, as prolonged severe iron deficiency anemia in early childhood can cause irreversible neurodevelopmental and cognitive deficits 2, 3.
Common Pitfall to Avoid
Do not assume thalassemia trait based solely on microcytosis and family history without checking ferritin levels. The low ferritin definitively establishes iron deficiency as the cause 1, 4.