METHEMOGLOBINEMIA SECONDARY TO FOOD PROTEIN-INDUCED ENTEROCOLITIS SYNDROME: CASE REPORT

Food protein-induced enterocolitis syndrome (FPIES) is a non-immunoglobulin E mediated food allergy syndrome that presents with broad symptoms ranging from recurrent emesis and lethargy to hypovolemic shock and metabolic derangements. Methemoglobinemia can be seen in FPIES, but a broad differential should be considered. This case report discusses a six-week-old infant presenting with a four-day history of emesis after feeds and decreased activity. Upon exam, patient was lethargic, pale, tachypneic, and hypoxemic requiring intubation. Labs exhibited metabolic acidosis and methemoglobinemia of unclear etiology with the remainder unremarkable for infectious sources. Genetic sequencing and hemoglobin electrophoresis were normal. Methemoglobinemia initially improved after methylene blue, but the patient required repeat doses due to rising methemoglobin after reintroduction of soy formula. It was later discovered the patient had developed pallor, lethargy, and projectile emesis within four hours of feeds after switching from cow's milk formula to soy protein formula a few days prior to this event. After transition to extensively hydrolyzed formula, the symptoms resolved and methemoglobin returned to normal value. Cases of FPIES can mimic sepsis and other more common conditions, as seen in this case. In severe cases of FPIES with cyanosis or hypoxemia, methemoglobinemia should be considered. Children with cow's milk or soy protein FPIES are at high risk for having multiple solid food FPIES. Food avoidance and special diets can become necessary to prevent adverse reactions, and supervised introduction of solids with an allergist can be considered for infants with a history of severe FPIES.