Hemoglobinuria

Excretion of free hemoglobin in urine, typically due to intravascular hemolysis, causing the kidneys to filter the excess hemoglobin and turn the urine a dark-red or brown color. Possible causes are hematologic disorders (sickle cell anemia, paroxysmal nocturnal hemoglobinuria), infections (urinary tract infection, pyelonephritis, tuberculosis, malaria), autoimmune/toxic reactions (blood transfusion, autoimmune hemolytic anemia, lead poisoning), physical trauma (march hemoglobinuria, severe burns), and kidney disease (hemolytic-uremic syndrome, thrombotic thrombocytopenic purpura, acute glomerulonephritis, renal cancer).