Dvanajscak Z, Walker PD, Cossey LN, et al. - Researchers sought to describe the clinicopathologic characteristics of hemolysis-associated hemoglobin cast nephropathy more comprehensively via performing a retrospective analysis of 27 cases who had renal biopsies reviewed in their laboratory. The patients had mean age of 47 years (range 19-79) and the female-to-male ratio of 1.3:1. Presentation with AKI with a mean serum creatinine of 8.0 (range 2.9-17.0) mg/dL was reported in all patients. Autoimmune hemolytic anemia (30%), adverse medication (26%), paroxysmal nocturnal hemoglobinuria (7%), procedural/mechanical causes (7%), transfusion of incompatible blood (4%), toxin ingestion (4%), disseminated intravascular coagulation (4%), and hemoglobinopathy (4%) were the identified etiologies in these cases. Acute tubular injury and pigmented, proteinaceous casts characterized by positive hemoglobin immunohistochemistry were evident in all biopsies. The mean serum creatinine was 1.3 (range 0.6-3.3) mg/dL after a mean follow-up of nine months (range 0.5-26) with a return to normal kidney function in 78% of patients. These clinicopathologic case series indicate hemolysis-associated hemoglobin cast nephropathy as a significant entity for clinicians and pathologists, as its treatment hinges upon removal of the pathogenic driver of intravascular hemolysis.