C3-03 Acquired Methemoglobinemia in an Infant With Chronic Malabsorptive Diarrhea

Introduction

Methemoglobinemia in an infant is a rare and potentially fatal condition resulting from the oxidation of ferrous iron in hemoglobin to ferric iron, which is unable to bind or transport oxygen, leading to functional anemia and hypoxemia. Congenital causes from genetic enzyme deficiencies are extremely rare. Acquired cases of methemoglobinemia are more common and can be due to chemical exposures, medications, or from endogenous causes such as sepsis, acidosis, or diarrhea.

Case Description

A 29 day old female with a history of poor weight gain and loose stools from birth was admitted for persistent metabolic acidosis in the setting of increased emesis and diarrheal losses. She was positive for rhinovirus/enterovirus; the remainder of her infectious work-up, including blood, urine, and cerebrospinal fluid cultures were negative. Despite supportive management with intravenous fluids and electrolyte replacements for presumed viral gastroenteritis, her symptoms persisted. She developed a worsening non-anion gap metabolic acidosis with electrolyte abnormalities including hypokalemia, hyperchloremia, and hypophosphatemia, progressively worsening anemia, failed to regain her birth weight, and after several weeks was found to have methemoglobinemia and hypoxemia. She was transferred to the pediatric intensive care unit for additional respiratory support with low-flow nasal cannula, packed red blood cell transfusion, and intravenous methylene blue. An extensive genetics work-up including whole genome sequencing to investigate the underlying mechanism of methemoglobinemia was ultimately unrevealing. Further work-up revealed low fecal elastase consistent with pancreatic insufficiency. She was started on pancreatic enzyme replacement therapy with feeds with normalization of her electrolyte balance and stool output, had several days of consistent weight gain, and was eventually discharged with further work-up to be completed outpatient.

Discussion

This case illustrates the diagnosis of methemoglobinemia in an infant with diarrhea, unresolving metabolic acidosis, and hypoxemia. Diarrhea is known to be associated with methemoglobinemia in infants and has been documented in prior case reports as often co-occurring with acute gastroenteritis in the neonatal period. In bacterial gastroenteritis, exposure to bacteria like escherichia coli and campylobacter can increase the nitrite burden in the gut leading to indirect oxidation of the ferrous iron in hemoglobin to a ferric state, creating methemoglobin. However this case report highlights a rare case of methemoglobinemia in an infant with chronic diarrhea due to underlying pancreatic insufficiency. Even in the absence of an identifiable bacterial etiology, malabsorptive diarrhea can be considered as a potential trigger for methemoglobinemia in infants.

This abstract is funded by: None