How is hematuria and hemoglobinuria distinguished in the evaluation of transfusion reactions?

Updated: Jan 12, 2021
  • Author: S Gerald Sandler, MD, FCAP, FACP; Chief Editor: Emmanuel C Besa, MD  more...
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Within minutes of an ABO blood group–incompatible transfusion, the recipient's urine may become red. To distinguish between hematuria (red cells from the lower urinary tract) and hemoglobinuria (hemoglobin monomers and dimers cleared from the plasma by the kidney), centrifuge the urine. As illustrated below, centrifuged urine from a patient with hematuria is clear yellow with red cells sedimented at the bottom of the tube. Urine from a patient with hemoglobinuria remains clear red and unchanged in color.

Rapid test to distinguish hematuria from hemoglobi Rapid test to distinguish hematuria from hemoglobinuria. The onset of red urine during or shortly after a blood transfusion may represent hemoglobinuria (indicating an acute hemolytic reaction) or hematuria (indicating bleeding in the lower urinary tract). If freshly collected urine from a patient with hematuria is centrifuged, red blood cells settle at the bottom of the tube, leaving a clear yellow urine supernatant. If the red color is due to hemoglobinuria, the urine sample remains clear red after centrifugation.

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