Why can't somebody with large red blood cells donate blood?

Question

A friend of mine wanted to donate blood but he was rejected because he was told his red blood cells are too large. Does it have something to do with antibodies not recognizing the cell during transfusion?

Answer 1

A number of conditions could result in large red blood cells.

These include anaemia
o Megaloblastic Anaemia such as from B12 or Folate deficiency

o Acute haemorrhage can cause an anaemia and a reactive reticulocytosis which might have been the cause of the large red blood cells (production of many immature red blood cells to compensate for the loss of RBC) as these immature forms (reticulocytes) are a little larger than the normal blood cells

o Spherocytosis can give rise to a reticulocytosis

o Liver disease, Thyroid disease, Bone Marrow disease can all give rise to large red blood cells

In all of these cases, your friend may well have been considered unsuitable to be a blood donor.

Answer 2

I work in a hospital lab and I can tell you that the size of RBC's is not routinely screened for blood donation. This would only show up in tests ordered by a Dr. Perhaps your friend told the donor center about it and they suspected that he has a form of RBC cancer. Large red blood cells are large because they are not fully mature. They shrink and expel their nucleus as they mature. If his are large then they must be abnormal due to some condition.

Answer 3

I would imagine that anyone with blood cells that are abnormal in some way would not be eligible to donate blood.