Microcytosis - Iron Deficiency or Hemoglobinopathy?

The presence of microcytosis may indicate iron deficiency vs. hemoglobinopathy. But before all the tests are back, can you distinguish between the two? Hematologist, Dr. Toyosi Onwuemene, shows us a way to make a quick educated guess.

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What about not having a normal mcv recorded by blood tests but having normal iron studies?