Syncope Following Treatment of UTI: A Case of Acute Hemolytic Anemia, Methemoglobinemia and Acute Renal Dysfunction Following Phenazopyridine Use in a Patient With G6PD Deficiency

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive genetic disorder which commonly affects males. It is due to a defect in the red blood cell enzyme, G6PD. Lack of G6PD makes the RBCs vulnerable to oxidant stress resulting in hemolysis. The severity of hemolytic anemia varies among individuals with G6PD deficiency. Here we present a case of an 80-year-old man admitted with syncope and jaundice. He was treated with phenazopyridine for a UTI 2 weeks ago. Subsequent investigation revealed G6PD deficiency as well as methemoglobinemia. Historically, phenazopyridine has been associated with causing methemoglobinemia and triggering hemolysis in G6PD deficient individuals. However, only a few cases have been reported in the last 60 years, making it a very rare occurrence.