ABSTRACT

Methemoglobinemia is a rare but potentially serious condition characterized by an increased level of methemoglobin in the blood, which impairs oxygen delivery to tissues. It occurs when hemoglobin’s ferrous iron (Fe2+) is oxidized to ferric iron (Fe3+), rendering it unable to bind oxygen effectively. This leads to tissue hypoxia, which can manifest clinically as cyanosis, shortness of breath, fatigue, and, in severe cases, organ dysfunction.

Nitrofurantoin-induced hemolytic anemia and methemoglobinemia in patients with glucose-6- phosphate dehydrogenase (G6PD) deficiency are rare but potentially life-threatening complications. We present the case of a 64-year-old female with G6PD deficiency who developed acute hemolytic anemia and methemoglobinemia following nitrofurantoin therapy for a urinary tract infection. Her initial symptoms included fatigue, jaundice, and dyspnea, progressing rapidly to severe anemia and cyanosis. Laboratory investigations confirmed hemolysis and elevated methemoglobin levels.

Although methemoglobinemia is commonly treated with methylene blue, its use in G6PD- deficient patients can exacerbate hemolysis. In this case, we promptly discontinued nitrofurantoin and managed the patient with hyperbaric oxygen therapy, intravenous ascorbic acid, and other supportive measures. Despite aggressive treatment, she required blood transfusion support and prolonged hospitalization.

This case underscores the importance of recognizing the potential for nitrofurantoin-induced hemolytic anemia and methemoglobinemia in G6PD-deficient individuals, highlighting the need for careful drug selection and vigilant monitoring in this population.

Keywords: case report; glucose-6-phosphate dehydrogenase deficiency; hemolytic anemia; hyperbaric oxygen therapy; methemoglobinemia; nitrofurantoin

Key Points:
Patients with G6PD deficiency are susceptible to drug-induced hemolytic anemia and methemoglobinemia. These conditions are typically managed with methylene blue,

intravenous vitamin C, and supportive measures. However, when methylene blue is contraindicated, managing methemoglobinemia becomes challenging. This case report highlights the critical role of hyperbaric oxygen therapy as an alternative treatment in such complex clinical scenarios.