What is paroxysmal nocturnal hemoglobinuria (PNH)?

Updated: May 20, 2021
  • Author: Emmanuel C Besa, MD; Chief Editor: Sara J Grethlein, MD, FACP  more...
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Answer

The name of the disorder is a descriptive term for the clinical consequence of red blood cell (RBC) breakdown with release of hemoglobin into the urine, which manifests most prominently as dark-colored urine in the morning (see image below).

This series of containers holds urine of a patient This series of containers holds urine of a patient with paroxysmal nocturnal hemoglobinuria, showing the episodic nature of the dark urine (hemoglobinuria) during intravascular hemolysis, usually occurring at night. Early morning urine is cola-colored. This may occur at different times of the day and vary from patient to patient. Permission to use this image has been granted by the American Society of Hematology Slide Bank, 3rd edition.

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