Nucleated Red Blood Cells

Red blood cells are referred to as erythrocytes in medical terms. These blood cells make up the major chunk of blood that helps carry oxygen and nutrients to each and every cell, tissue, organ and part of the body through the circulatory system. Under normal circumstances, RBCs appear as flexible, biconcave disks. On further microscopic examination, one observes these cells lack a cell nucleus and most of the cellular organelles. Thus, when presence of nucleated red blood cells in their peripheral blood film is detected, one gets alarmed. This is a sign that the person may be suffering from an underlying health problem.

Why is RBC Count Ordered?

RBC count is always a part of the complete blood count (CBC) test. This test may be ordered as a part of routine physical checkup, or pre-surgical and clinical reasons. Patients with chronic anemia, bleeding problems, hematologic disorders are regularly asked to undergo complete blood count tests. A blood smear test helps the doctor learn more about the blood cell irregularities in their size, shape, color as well as observe nucleated RBCs.

What is the Significance of Nucleated Red Blood Cells?

Nucleated red blood cells are called normoblasts. They are red blood cells that retain the cell nucleus. These cells are actually precursors for production of normal erythrocytes. These immature RBCs are commonly observed in neonates. Thus, nucleated red blood cells in newborns is not usually a cause for concern. These nucleated RBCs (NRBCs) are present in the peripheral blood of normal newborns up to 5 days after their birth. However, appearance of nucleated red blood cells in adults as well as children indicates there may be damage to the bone marrow, stress or presence of serious underlying disease. Some of the conditions, where one reports presence of NRBCs are as follows:

Asplenia and Hyposplenism
It is possible under normal conditions, for normoblasts to escape the bone marrow and enter the blood stream. However, they are immediately destroyed by the spleen. If at all one observes NRBCs in the blood, it may suggest hyposplenism. This is a condition where the splenic function has been reduced to some extent. In case, splenic function is totally absent, it is called asplenia. This state is usually observed in patients with myeloproliferative disorders as well as sickle-cell disease. Conditions where bone marrow releases too many NRBCs, cause an overload on the spleen to remove their presence from the blood. These conditions that cause excessive release of NRBCs include hypoxia, hemolytic anemia, treatment induced anemia, malignant neoplasms, collagen vascular diseases or chemotherapy.

Severe Anemia
When a patient suffers from severe anemia, the oxygen carrying capacity of RBCs is greatly reduced. Thus, hypoxic erythropoietin-induced compensatory erythropoiesis induces production of normoblastemia. Tissue cells suffer from hypoxia that stimulates the kidneys to produce erythropoietin. This causes intense production of blood cells in the bone marrow. If the process is effective, it will lead to production of reticulocytosis, polychromasia and NRBCs at times. In case erythropoiesis is ineffective, it causes excessive production of NRBCs that are released prematurely in the peripheral blood.

Hypoxia
When the body or a particular body tissue does not receive adequate supply of oxygen it leads to hypoxia. Apart from anemia, hypoxia can result due to underlying cardiopulmonary disorders. These cardiopulmonary disorders reduce the capacity of the blood to absorb oxygen. These NBRCs are also present in patients suffering from pulmonary embolism as well as coronary thrombosis.

Conditions that Lead to Presence of Nucleated Red Blood Cells

There are many other health conditions that may lead to presence of these NRBCs in peripheral blood film. To help you know these conditions, the following table will prove to be a helpful read.

Conditions that Lead to Presence of NRBCs	Causative Factors
Bone marrow replacement or invasion	Preleukemia Neuroblastoma Osteopetrosis Plasma cell myeloma Severe pulmonary disease Presence of tumor cells
Anemia due to compensatory erythropoiesis	Treatment causing anemia Iron deficiency anemia Severe anemia Hemolytic anemia Hemorrhage Thalassemia major
Hyposplenism, asplenia	Essential thrombocytosis Hemolytic anemia Malaria Newborn (physiological condition) Sickle cell anemia Splenectomy
Hypoxia	Collagen vascular disease Fungal infection Gaucher Granuloma (tuberculosis) Histiocytosis Leukemia Congestive cardiac failure Cyanotic heart disease Lymphoma
Extramedullary hematopoiesis	Chronic hemolytic anemia Myeloid metaplasia Osteopetrosis Polycythemia vera Myelophthisis Leukemia Myelofibrosis

As you can see, there are many conditions that lead to nucleated red blood cells in adults. It is important to correct NBRCs as they not only affect the WBC count, but also have serious health consequences in some patients. Thus, a lab report has to mention even the presence of 1 NRBC/100 WBCs. One should keep in mind, the appearance of NRBCs in blood itself does not help in diagnosis of a particular disease. It is just a tool that indicates a situation wherein a serious underlying disease may be present. Thus, helping the patient to get medical intervention as early as possible.