Assuming the bone marrow is normal and there are sufficient erythropoeitin and iron stores, acute anemia (ie. hemolysis or blood loss) should increase the retic % to 4-6%
[errolozdalga.com]
[…] cramps Back pain Intermittent episodes of hemoglobinuria Typical laboratory findings Elevated bilirubin level Decreased hemoglobin Polychromatophilia, nucleated RBCs, and poikilocytosis
[labce.com]
The peripheral blood smear exhibits spherocytosis, polychromasia, nucleated red blood cells (RBCs), anisocytosis, poikilocytosis, and sometimes erythrophagocytosis by neutrophils
[emedicine.com]