Methemoglobinemia With Dapsone Prophylaxis in a Patient With Minimal Change Disease

Our case report represents the need to maintain vigilance for methemoglobinemia risk in patients without classic symptoms, specifically, in patients that develop shortness of breath after starting prophylaxis for Pneumocystis jiroveci pneumonia, mostly with dapsone. A case report of a 42-year-old male with minimal change disease nephrotic syndrome required Pneumocystis jiroveci pneumonia prophylaxis due to high-dose systemic steroids. The patient was started on dapsone due to side effects and the availability of alternative medications. Since starting therapy, the patient developed progressive dyspnea upon exertion for two weeks with intermittent hypoxia. The patient tested negative for glucose-6-phosphate dehydrogenase deficiency prior to starting dapsone. He was also on therapeutic enoxaparin due to a hypercoagulability state from nephrotic syndrome. The patient presented with hypoxia and dyspnea upon exertion, however, speaking in complete sentences and with no cyanosis or overt findings of hypervolemia. The patient remained hypoxemic despite supplemental oxygen. An arterial blood gas was performed and showed methemoglobin levels of 10.6 percent. He was treated with methylene blue with the resolution of methemoglobinemia and hypoxemia after a second dose. Trimethoprim-sulfamethoxazole was started for Pneumocystis jiroveci pneumonia prophylaxis. He was safely discharged home.