Methemoglobinemia in a young male with complex multisystem comorbidities

The present report discusses a case of methemoglobinemia in a 32-year-old male with a complex medical history, including focal segmental glomerulosclerosis, antiphospholipid antibody syndrome (APLA), and coagulation factor VII and IX deficiencies. He presented with acute cyanosis, brown-colored urine, and dyspnea at rest, without complaints of chest pain, palpitations, or syncope. Arterial blood gas analysis revealed elevated methemoglobin levels (31.8%) despite normal arterial oxygenation. Treatment with methylene blue led to symptomatic improvement but was complicated by hemolytic anemia after 4–5 days. This case highlights the diagnostic and therapeutic challenges of managing methemoglobinemia in patients with underlying autoimmune and hematologic disorders.