Acquired methemoglobinemia in infancy secondary to diarrhea: a case report.

Methemoglobinemia (MetHb) is a life-threatening condition that reduces the oxygen-carrying ability of hemoglobin. Acquired methemoglobinemia usually results from exposure to specific oxidizing agents. Symptoms and complications depend on the MetHb level, which can sometimes be fatal. We present a case of a 6-week-old infant exhibiting hypoxia alongside gastroenteritis, fever, poor oral intake and low activity, with confirmed methemoglobinemia in blood gas analysis. Despite negative results in the workup for underlying causes, including genetic testing conducted later, methylene blue administration only partially reduced methemoglobinemia level. Treatment involved managing diarrhea by transitioning to a hydrolyzed formula. Interestingly, an incidental discovery of partial central venous sinus thrombosis occurred during the diagnostic process, although no established correlation with methemoglobinemia was evident in the literature. This case report illustrates the complex presentation of methemoglobinemia in a previously healthy infant, occurring concurrently with gastrointestinal infection and unexpected thrombosis. It underscores the need for interdisciplinary collaboration and comprehensive management in addressing such multifaceted clinical scenarios in pediatric practice. This case emphasizes the importance of considering diarrhea as a possible cause of methemoglobinemia, especially in infancy. It also highlights the need for increased clinical awareness and prompt management approaches towards the various presentations of acquired methemoglobinemia in pediatric populations.