Nucleated red blood cells are a reflection of extreme increases in erythropoietic activity as seen in/with:
Hemoglobinopathies Brisk hemolysis Rapid blood loss Other conditions of hematopoietic stress such as sepsis Damage or stress to bone marrow, for example in: Chronic myeloid leukemia Acute leukemia Myelodysplastic syndromes Chemotherapy Myelophthisic conditions, including: Metastatic cancer to bone marrow Bone marrow fibrosis