Hemolysis
Chronic and excessive hemolysis (the destruction of red blood cells) is the main
cause of serious health problems in people with PNH.9 Hemolysis can
be measured by LDH (lactate dehydrogenase), an enzyme that is found in many organs
and tissues of the body, but is especially abundant in red blood cells. Elevated
levels of LDH are an indicator of excessive hemolysis.8
Destruction of Red Blood Cells
In healthy individuals, red blood cells are equipped with a surface protein, known
as a complement inhibitor, which protects them from naturally occurring levels of
complement and prevents cell destruction. Patients with PNH lack the protective
complement inhibitor protein, thus allowing red blood cells to be susceptible to
low levels of complement activity, leading to excessive hemolysis.7 When
excessive hemolysis occurs, the toxic contents of red blood cells are released into
the bloodstream and cause many of the symptoms associated with PNH.