The Role of Hemolysis in PNH
Hemolysis is a medical way of saying “destruction of red blood cells.” Hemolysis is measured by LDH (lactate dehydrogenase, an enzyme found in red blood cells) and elevated levels of LDH are an indicator of excessive hemolysis.1 In healthy people, low levels of hemolysis are constant and naturally occurring. However, in people with PNH, there is excessive hemolysis resulting from a missing protective surface protein on some or all RBCs. This excessive hemolysis releases the toxic contents of RBCs into the bloodstream, which, over time, can cause many of the symptoms associated with PNH and harm important organs in your body.
If you have PNH, hemolysis is always taking place — whether you feel OK or whether you’re having a flare-up (paroxysm), such as during times of stress or infection.1-4 Excessive and continual hemolysis is the main cause of major health problems in PNH.
Why is hemolysis important?
When blood cells are destroyed, their toxic contents are released into the bloodstream and can build up, causing health problems that can occur suddenly at any time.3,4 These problems can include kidney failure and serious blood clots, which may cause damage to important organs like your liver, brain, and lungs.1
Hemolysis also affects the way you feel. Many people with PNH report that the unpredictability of the frequency and severity of their symptoms impairs their quality of life. Physicians believe reducing chronic hemolysis is an important goal in PNH treatment.

Talk to your doctor about what you can do to reduce the risk of chronic hemolysis
