Q. Bite cell in G6PD…what is it? How is that different than a spherocyte?

A. In glucose-6-phosphate dehydrogenase deficiency, there isn’t enough G6PD around, so there isn’t enough NADPH around, so the toxic metabolites end up damaging the cell. Heme breaks apart from globin, and the globin chains ball up and stick to the inside of the RBC membrane (that’s called a Heinz body). The macrophages in the spleen see these Heinz bodies and “bite” them out, leaving a bite mark.

A spherocyte is a balled up red cell, smaller than a normal cell without a zone of central pallor. It’s present in any kind of hemolytic anemia; just about any odd-shaped red cell will ball up into a sphere after bouncing around the circulation long enough.