Red blood cells


Reticulocytes are immature red blood cells that develop in the bone marrow. They are important for measuring the body's ability to produce new red blood cells and can be used to evaluate bone marrow function and in the diagnosis of various blood disorders.

What Are Reticulocytes?

Retriculocytes are immature red blood cells, or precursors to red blood cells. These cells are a crucial part of the process by which the body produces new red blood cells, which is essential for maintaining efficient oxygen transport throughout the body. When the bone marrow generates new red blood cells, they go through a developmental phase (Erythropoiesis), including the stage when the development of reticulocytes occurs. In simplified terms, reticulocytes are roughly one step away from becoming fully mature red blood cells. They still lack a cell nucleus and other organelles that fully mature red blood cells possess.

Reticulocytes are often characterized by small remnants of the cell nucleus, which differentiates them from fully mature red blood cells that lack a cell nucleus. This nuclear remnant disappears during the reticulocyte's maturation process. When reticulocytes are fully mature, they are released into the bloodstream, where they can live for approximately 1-2 days before transforming into red blood cells.

Why Are Reticulocytes Analyzed?

Analysis of reticulocytes is used to evaluate various hematological (blood-related) conditions, such as hemolytic anemia, or to monitor bone marrow function. Therefore, it is an essential analysis for understanding and treating diseases or conditions that affect blood formation, anemia (a deficiency of red blood cells or hemoglobin), the assessment of iron deficiency, and in medical treatments.

What Can an Elevated Level of Reticulocytes Indicate?

An elevated level of reticulocytes is called reticulocytosis and can be due to several factors. Below are a few common causes.

  • Reticulocytosis anemia, a condition involving the loss of red blood cells due to bleeding or hemolysis. The body responds to anemia by increasing the production of reticulocytes to compensate for the lack of red blood cells.
  • Acute blood loss, such as from injury, can lead to a rapid increase in reticulocytes to restore blood volume and oxygen transport.
  • Hemolytic anemia, conditions that cause the premature destruction of red blood cells, resulting in an increase in reticulocytes as the body tries to replace the lost red blood cells.
  • High-altitude training, during training at high altitudes when oxygen uptake is impaired, a natural increase in reticulocytes can occur to compensate for the body's reduced oxygen-carrying capacity.
  • What Can a Low Level of Reticulocytes Indicate?

    Low levels indicate the condition of reticulocytopenia, which can be caused by several medical conditions. Here are some common causes of a decrease in reticulocyte levels.

    • Bone marrow disorders, such as aplastic anemia or myelodysplastic syndrome (MDS), can affect the bone marrow's ability to produce red blood cells, including reticulocytes.
    • Nutritional deficiencies, deficiencies in nutrients such as iron, vitamin B12, or folic acid can affect the production of red blood cells and reticulocytes.
    • Infections, certain viral infections such as HIV can affect the bone marrow and result in a decrease in reticulocytes.
    • Chronic kidney disease, in cases of chronic kidney failure, a decrease in reticulocytes can occur due to impaired production of erythropoietin, a hormone that stimulates red blood cells.

    What Is the Reference Range for Reticulocytes?

    A typical reference range for reticulocytes is usually between 0.5% and 2.5% of the total number of red blood cells. This means that reticulocytes are expected to make up this percentage range of all red blood cells in the blood. Note that the reference range may vary depending on the laboratory and the technique used to conduct the analysis. Generally, the reference range for an adult is between 30 - 110 x10^9/L.

Tests containing the marker Reticulocytes

Complete blood count

Complete blood count

Anemia investigation


  • Analysis of reticulocytes.
  • The precursor stage of your red blood cells.
  • Gain deeper insights into your blood status.

89 kr

Health checks

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