Suspected Sildenafil-Induced Immune Hemolytic Anemia Precipitating Acute Kidney Injury Requiring Hemodialysis

Drug-induced immune hemolytic anemia (DIIHA) is a rare secondary cause of autoimmune hemolytic anemia (AIHA), more frequently associated with drugs such as cephalosporins, penicillin, non-steroidal anti-inflammatory drugs (NSAIDs), and certain chemotherapeutic agents. The condition is often underdiagnosed due to marked variability in antibody type and affinity, resulting in inconsistent serological findings. Such delays increase the risk of hemolytic crisis, which may result in target end-organ failure or death. We report the case of a 26-year-old man with no prior comorbidities. He presented to our emergency department with an acute history of passing dark-colored urine, followed by reduced urine output for two days. Preliminary laboratory investigations revealed severe anemia, elevated lactate dehydrogenase, and indirect hyperbilirubinemia, suggesting a hemolytic pathology and a strongly positive direct antiglobulin test (DAT), which was consistent with a diagnosis of immune hemolytic anemia. This presentation was complicated by severe acute kidney injury (AKI). The patient's renal parameters progressively improved after initiating renal replacement and corticosteroid therapy. Despite extensive investigations, no underlying trigger for immune-mediated hemolysis could be identified. It was at this point that the patient disclosed recent recreational use of sildenafil citrate before symptom onset. Utilizing the Naranjo adverse drug reaction probability scale, we were able to isolate sildenafil as a probable trigger for immune-mediated hemolysis. The present case raises the possibility of sildenafil as a previously unreported trigger for drug-induced immune hemolytic anemia (DIIHA).