Case Presentation: A 23 month old female with minimal primary care visits presented to the ED after a syncopal episode. She was found to be tachycardic, tachypneic, and hypoxic. Physical exam revealed an irritable, pale child with a 3/6 systolic murmur and hepatomegaly. CBC was significant for a Hgb of 1.5. CXR revealed cardiomegaly.
Due to the concern for heart failure, the patient was admitted to the PICU where she received serial pRBC transfusions. Echocardiogram showed left ventricular dilation. Iron studies were significant for profound iron deficiency anemia. Further history revealed the patient transitioned to whole milk from formula around 11 months old but failed to begin intake of solid foods. Her parents reported she drank 32-40oz of milk bottles per day with little other nutrition. She also enjoyed “chewing socks” as a comfort mechanism, likely a manifestation of pica.

After stabilization, the patient worked with nutrition to increase solid food intake and limit cow’s milk. Gastroenterology and Hematology were consulted to rule out comorbid causes of anemia; work up thus far has been negative. At the time of discharge she was gaining weight and eating solids, supplemented with elemental iron.

Discussion: Iron deficiency anemia is a common problem in the pediatric population, and is of particular concern due to its negative effects on growth and neurodevelopmental outcomes. Excessive cow’s milk consumption is a common mechanism for iron deficiency anemia; one study found the early use of cow’s milk in a child’s diet increased the risk of iron deficiency by 39% with every subsequent month of use. Excessive cow’s milk consumption causes iron deficiency primarily due to its relatively low iron content; however, microscopic intestinal blood loss due to inflammation and inhibition of iron absorption may also play a role.

High output heart failure is a rare extreme complication of iron deficiency anemia, with few reported cases. Much of the pathophysiology of heart failure due to iron deficiency anemia is extrapolated from adult literature, but it appears to occur via three mechanisms. First, a compensatory increase in heart rate and stroke volume occurs in order to increase oxygen delivery to the tissues, leading to cardiomyopathy. Second, vasodilation may occur due to low blood viscosity which leads to neurohormonal release and low vascular resistance. Finally, iron deficiency anemia may cause direct myocyte injury. Correcting the underlying iron deficiency leads to resolution of the myopathy.

Conclusions: Excessive intake of cow’s milk is a common cause of iron deficiency anemia in children and is significant for its negative effects on growth and neurodevelopmental outcomes. In rare cases, profound iron deficiency anemia can lead to high output heart failure as described in this case.