What is the classic symptom of 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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The classic manifestation of paroxysmal nocturnal hemoglobinuria (PNH) is dark urine during the night with partial clearing during the day (see image below). However, hemoglobinuria may occur every day in severe cases; more frequently, it occurs in episodes lasting 3-10 days; and in some cases, it does not occur at all.

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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