Could hematocrit or rbc count, have an impact on the diagnosis and treatment of iron deficiency anemia?

Yes: Hematocrit is the amount of redcells present in a sample of whole blood. Rbc count is the number of red cells in a specific volume of whole blood. In both cases we would expect these numbers to be low if a patient is anemic. The MCV is usually low in iron deficiency as well. Iron studies and ferritin are necessary to confirm the diagnosis of iron deficiency anemia.