Methemoglobinemia in childhood from green leafy vegetables: the importance of consumption and stor age guidelines for these foods

Abstract

Methemoglobinemia is an uncommon but potentially life-threatening cause of tissue hypoxia, particularly relevant in the pediatric population. It results from the oxidation of hemoglobin iron to the ferric state, impairing oxygen transport and leading to cyanosis unresponsive to oxygen therapy. We report the case of a 12-month-old infant who presented to a secondary-level emergency department with progressive cyanosis over 24 hours. Initial assessment revealed oxygen saturation of 84% despite 100% inspired oxygen, with otherwise stable vital signs. Medical history revealed the consumption over several days of homemade vegetable purée containing leafy greens that had been partially refrigerated. Blood gas analysis confirmed methemoglobin levels above 30%, without metabolic acidosis or hyperlactatemia. The patient was treated with intravenous methylene blue, resulting in rapid clinical and laboratory improvement. This case highlights the importance of early recognition of methemoglobinemia in emergency and primary care settings and underscores the role of proper food handling education in preventing nitrate-induced methemoglobinemia in infants.