Home Biomarkers Nucleated red blood cells

Nucleated red blood cells

CBC Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: CBC

Overview

Nucleated red blood cells (NRBCs) are immature erythroid precursors that normally mature in the bone marrow and lose their nucleus before entering the peripheral blood as mature red blood cells. A laboratory test for NRBCs counts these immature cells in a peripheral blood smear or reports an absolute NRBC count on an automated CBC with differential. NRBCs in peripheral blood suggest bone marrow stress or interruption of normal maturation—common causes include severe hypoxia, acute blood loss or hemolysis, bone marrow infiltration (leukemia, myelofibrosis), sepsis, or recovery after marrow suppression. They are normally absent in healthy adults; neonates frequently have measurable NRBCs immediately after birth, and counts vary with age, pregnancy, and physiologic stressors.

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Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: included as part of a CBC (complete blood count) with differential or ordered when a peripheral smear is examined.
Symptoms: unexplained anemia, pallor, fatigue, rapid heart rate, signs of infection, bleeding, or neonatal distress.
Use: diagnose/monitor marrow stress, severe hypoxia, hemolysis, sepsis, marrow disorders or response to therapy.
Abnormal levels reflect premature marrow release or extramedullary erythropoiesis; causes include hypoxia, hemorrhage, infection, marrow infiltration.
Lifestyle/family history: smoking, high-altitude exposure, or family history of hematologic disease may prompt testing.

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Understanding Test Results

Any detectable NRBCs in an adult peripheral blood sample (i.e., >0/100 WBC or >0/μL) is abnormal and signals significant marrow stress or pathology.
Low-level presence (1–5 NRBCs/100 WBC) often indicates mild to moderate marrow response to anemia, recent hemorrhage, or infection.
Moderate counts (≈6–20/100 WBC) suggest more severe hypoxia, hemolysis, severe infection/sepsis, or marrow infiltration.
Very high counts (>20 NRBCs/100 WBC or markedly elevated absolute NRBCs) are associated with critical illness and poorer prognosis (e.g., severe hypoxic injury, advanced marrow disease such as acute leukemia or myelofibrosis).
In neonates, up to ~20/100 WBC in the first 24–48 hours can be physiologic; persistent or rising counts beyond the neonatal period suggest pathology (perinatal hypoxia, infection, hemolysis) and warrant further evaluation.

Normal Range

Adults: 0/100 WBC OR 0/μL; Neonates (first 24–48 hrs): 0–20 NRBCs/100 WBC OR up to ~0.1–0.2/μL

FAQs

Q: What does it mean when your red blood cells are nucleated?

A: Nucleated red blood cells (NRBCs) are immature erythrocytes normally confined to bone marrow. Their presence in peripheral blood indicates increased or premature marrow release due to severe anemia, hemolysis, hypoxia, infection, marrow stress or infiltration, or recovery after chemotherapy; they’re normal in newborns but abnormal in adults and should prompt further clinical evaluation.

Q: What is a normal NRBC level?

A: Normal NRBC (nucleated red blood cell) level in peripheral blood is essentially zero in healthy adults—NRBCs are not normally present. In newborns, small numbers can be normal immediately after birth; commonly up to about 10–30 NRBCs per 100 white blood cells, declining to zero within days. Detectable NRBCs in older children or adults warrant further evaluation.

Q: What does it mean if nucleated cells are high?

A: High nucleated cells (nucleated red blood cells) in peripheral blood mean immature red cells are being released from the bone marrow. This usually reflects marrow stress or injury severe anemia or hemolysis, hypoxia, serious infection/sepsis, acute blood loss, marrow infiltration (for example leukemia), or extramedullary hematopoiesis. Normal in newborns, abnormal in older children/adults and needs prompt medical evaluation.

Q: What disease is nucleated RBC found in?

A: Nucleated red blood cells (normoblasts) in peripheral blood indicate marrow stress or immature erythropoiesis. Common causes include severe hemolytic anemia, thalassemia, extramedullary hematopoiesis, bone marrow infiltration (leukemia, myelofibrosis), severe infection/sepsis, hypoxia, or post-splenectomy states. In newborns they can be physiological. Their presence warrants prompt evaluation for underlying marrow disease or severe systemic illness.

Q: Can nucleated red blood cells go away?

A: Nucleated red blood cells (NRBCs) can disappear once the underlying cause—severe anemia, hypoxia, infection, bone marrow stress, or newborn adaptation—is treated or resolves. In adults their presence is abnormal and usually resolves with recovery; persistent NRBCs suggest bone marrow disease or ongoing severe stress and require further evaluation. Follow-up blood counts monitor progress.

Q: Can infection cause nucleated RBC?

A: Yes. Severe infections—especially sepsis or widespread inflammation—can lead to nucleated red blood cells (NRBCs) appearing in peripheral blood by stressing bone marrow, causing premature release or triggering extramedullary hematopoiesis. NRBCs in adults are abnormal, often indicate serious illness (hypoxia, marrow injury, hemolysis, or infiltration) and warrant prompt clinical evaluation and management.