What’s with all the reticulocytes?

Reticulocytes in PK deficiency (PKD)

• Compared with other hereditary hemolytic anemias, PKD is associated with a far greater post-splenectomy reticulocytosis, with reticulocytes reaching 50% or more over pre-splenectomy counts.
• The mechanism(s) involved in this unique pathophysiological feature of PKD is not understood, but presumably relate to selective destruction of relatively young PK-deficient reticulocytes by the spleen.
• Reticulocytes have a much higher ATP requirement compared with mature red blood cells but because they still have mitochondria, they can rely on oxidative phosphorylation for energy. However, in the hypoxic splenic environment, PK-deficient reticulocytes are forced to use glycolysis, which does not meet their high ATP needs, leading to hemolysis. In the absence of the spleen, reticulocyte survival increases.