What is the diagnosis for a pediatric boy with a restrictive diet of milk and bread, presenting with pallor and fatigue, low hemoglobin (Hg), microcytosis (low MCV), hypochromia (low MCH), low ferritin, and elevated reticulocytes (Retics)?

Diagnosis: Iron Deficiency Anemia (IDA)

The diagnosis is iron deficiency anemia (IDA), option 3, based on the classic presentation of a toddler with excessive milk and bread consumption, microcytic hypochromic anemia (low Hg, low MCV, low MCH), low ferritin confirming depleted iron stores, and elevated reticulocytes indicating appropriate bone marrow response to the anemia. 1, 2

Clinical Reasoning

Dietary History Confirms the Etiology

• Excessive milk consumption is the primary cause of IDA in toddlers, as cow's milk contains minimal iron, displaces iron-rich foods from the diet, and can cause occult gastrointestinal blood loss 1, 3
• Children consuming >24 ounces of cow's milk daily are at high risk for severe IDA, with studies showing 47 of 48 children with severe IDA consumed more than 24 ounces daily, and some exceeded 64 ounces 3
• The diet of only milk and bread provides inadequate dietary iron and represents a classic nutritional pattern leading to IDA in this age group 1, 2

Laboratory Pattern is Pathognomonic for IDA

• Low ferritin (<30 μg/L in children >15 years, <15 μg/L in children 6-12 years, <20 μg/L in adolescents 12-15 years) definitively confirms iron deficiency and distinguishes IDA from other microcytic anemias 1
• The combination of microcytosis (low MCV) and hypochromia (low MCH) reflects iron-deficient erythropoiesis, where red blood cells are produced with progressively less hemoglobin content 1, 2
• Elevated reticulocytes indicate appropriate bone marrow response, ruling out production disorders like aplastic anemia or bone marrow infiltration 1

Why Other Diagnoses Are Excluded

Lead poisoning (option 1) would present with:

• Basophilic stippling on peripheral smear
• Elevated erythrocyte protoporphyrin (>80 μg/dL in children 1-2 years)
• Normal or elevated ferritin (lead poisoning can coexist with IDA but doesn't cause low ferritin)
• Neurodevelopmental symptoms, abdominal pain, or pica for non-food items 1

Hereditary spherocytosis (option 2) would show:

• Spherocytes on peripheral smear
• Elevated mean corpuscular hemoglobin concentration (MCHC), not low
• Positive family history of hemolytic anemia
• Splenomegaly and jaundice
• Normal or elevated ferritin from chronic hemolysis 1, 4

Anemia of chronic disease (option 4) would demonstrate:

• Normal or elevated ferritin (>30 μg/L), as ferritin is an acute phase reactant
• Low transferrin saturation with elevated ferritin
• Evidence of underlying chronic inflammatory condition
• The low ferritin in this case definitively excludes this diagnosis 1, 5

Treatment Approach

Immediate Management

• Prescribe oral iron at 3-6 mg/kg/day of elemental iron between meals to maximize absorption 1, 2
• Ferrous sulfate preparations containing 28-50 mg elemental iron per dose minimize gastrointestinal side effects while maintaining efficacy 6
• Provide intensive dietary counseling to limit cow's milk to <24 ounces daily and introduce iron-rich foods (meat, fortified cereals, beans) 1, 3

Monitoring Response

• Recheck hemoglobin in 4 weeks; an increase of ≥1 g/dL confirms the diagnosis and adequate treatment response 1
• If confirmed, continue iron therapy for 2 additional months to replenish iron stores, then recheck hemoglobin 1
• Reassess hemoglobin approximately 6 months after completing treatment 1

Critical Pitfall to Avoid

• Failure to address excessive milk consumption will result in treatment failure despite iron supplementation, as the underlying dietary cause persists 7, 3
• Severe IDA in toddlers (hemoglobin <7 g/dL) can cause life-threatening complications including cerebral sinovenous thrombosis due to hypercoagulability from iron deficiency 7
• When present in early childhood, especially if severe and prolonged, IDA can cause irreversible neurodevelopmental and cognitive deficits even after correction of the anemia 2, 3