Nucleated red blood cell

A human peripheral blood smear; NRBCs are visible as larger cells with dark centers.

A nucleated red blood cell (NRBC), also known by several other names, is a red blood cell that contains a cell nucleus. Almost all vertebrate organisms have hemoglobin-containing cells in their blood, and with the exception of mammals, all of these red blood cells are nucleated.[1] In mammals, NRBCs occur in normal development as precursors to mature red blood cells in erythropoiesis, the process by which the body produces red blood cells.

NRBCs are normally found in the bone marrow of humans of all ages and in the blood of fetuses and newborn infants.[2][3] After infancy, RBCs normally contain a nucleus only during the very early stages of the cell's life, and the nucleus is ejected as a normal part of cellular differentiation before the cell is released into the bloodstream. The presence of circulating NRBCs in adults occurs in situations of hematopoietic stress such as severe infection, massive hemorrhage, marrow infiltration, or extramedullary hematopoiesis.[4] That is, if NRBCs are identified on an adult's complete blood count or peripheral blood smear, it suggests that there is a very high demand for the bone marrow to produce RBCs, and immature RBCs are being released into circulation. Possible pathologic causes include anemia, myelofibrosis, thalassemia, miliary tuberculosis, cancers involving bone marrow (myelomas, leukemias, lymphomas), and in chronic hypoxemia.[5]

  1. ^ Hartenstein, V (2006). "Blood cells and blood cell development in the animal kingdom" (PDF). Annu Rev Cell Dev Biol. 22: 677–712. doi:10.1146/annurev.cellbio.22.010605.093317. PMID 16824014. Retrieved October 28, 2016.
  2. ^ Greer, JP; Arber, DA; Glader, BE; List, AF; Means, RM; Rodgers, GM (19 November 2018). "Chapter 1: Examination of the Blood and Bone Marrow, sec. "Nucleated Red Blood Cell Counts"". Wintrobe's Clinical Hematology (14th ed.). Wolters Kluwer Health. ISBN 978-1-4963-6713-6.
  3. ^ Kottke-Marchant, K; Davis, B (6 June 2012). Laboratory Hematology Practice. John Wiley & Sons. p. 294. ISBN 978-1-4443-9857-1.
  4. ^ Shehata, Amira M.F. (2020-09-30). "Clinical significance of nucleated red blood cell count in pediatric patients with transfusion-dependent beta thalassemia". Menoufia Medical Journal. 33 (3): 949–955.
  5. ^ Blood Smear: Details on RBCs, WBCs