If your results show a higher than normal amount of reticulocytes (reticulocytosis), it may mean:
- You have hemolytic anemia, a type of anemia in which red blood cells are destroyed faster than the bone marrow can replace them.
- Your baby has hemolytic disease of the newborn, a condition that limits the ability of a baby's blood to carry oxygen to organs and tissues.
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Acute or chronic bleeding (hemorrhage) or increased RBC destruction (hemolysis) can lead to fewer RBCs in the blood, resulting in anemia. The body compensates for this loss or to treatment of deficiency anemias (such as iron deficiency anemia or pernicious anemia) by increasing the rate of RBC production and by releasing RBCs sooner into the blood, before they become more mature. When this happens, the number and percentage of reticulocytes in the blood increases until a sufficient number of RBCs replaces those that were lost or until the production capacity of the bone marrow is reached.
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In general, the reticulocyte count (absolute number or percentage) is a reflection of recent bone marrow activity. Results may indicate whether a disease or condition is present that is generating an increased demand for new RBCs and whether the bone marrow is able to respond to the extra requirement. Occasionally, results may indicate overproduction of RBCs.
When anemia is present (i.e., low RBCs, low hemoglobin, low hematocrit) and the bone marrow is responding appropriately to the demand for increased numbers of RBCs, then the bone marrow will produce more and allow for the early release of more immature RBCs, increasing the number of reticulocytes in the blood.
A high reticulocyte count with low RBCs, low hemoglobin, and low hematocrit (anemia) may indicate conditions such as:
- Bleeding: If you bleed, then the number of reticulocytes will rise a few days later in an attempt to compensate for the red cell loss. If you have chronic blood loss, then the number of reticulocytes will stay at an increased level as the marrow tries to keep up with the demand for new RBCs (although it may not be high if the blood loss leads to iron deficiency).
- Hemolytic anemia: In this condition, anemia is caused by increased destruction of RBCs. The bone marrow increases RBC production to compensate, resulting in a high reticulocyte count.
- Hemolytic disease of the newborn: This condition causes increased RBC destruction, similar to hemolytic anemia described above.
If your results show a lower than normal amount of reticulocytes, it may mean you have:
- Iron deficiency anemia, a type of anemia that happens when you don't have enough iron in your body.
- Pernicious anemia, a type of anemia caused by not getting enough of certain B vitamins (B12 and folate) in your diet, or when your body can't absorb enough B vitamins.
- Aplastic anemia, a type of anemia that happens when the bone marrow isn't able to make enough blood cells.
- Bone marrow failure, which may be caused by an infection or cancer.
- Kidney disease
- Cirrhosis, scarring of the liver
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Decreased RBC production may occur when the bone marrow is not functioning normally. This can result from a bone marrow disorder such as aplastic anemia. Diminished production can also be due to other factors, for example, cirrhosis, kidney disease, radiation or chemotherapy treatments for cancer, a low level of the hormone erythropoietin, or deficiencies in certain nutrients such as iron, vitamin B12 or folate. Decreased production leads to fewer RBCs in circulation, decreased hemoglobin and oxygen-carrying capacity, a lower hematocrit, and a reduced number of reticulocytes as old RBCs are removed from the blood but not fully replaced.
Occasionally, both the reticulocyte count and the RBC count will be increased because of excess RBC production by the bone marrow. This may be due to an increased production of erythropoietin, disorders that cause chronic overproduction of RBCs (polycythemia vera), and cigarette smoking.
Some drugs may increase or decrease reticulocyte counts.
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A low reticulocyte count with low RBCs, low hemoglobin, and low hematocrit (anemia) may be seen, for example, with:
- Iron deficiency anemia
- Pernicious anemia or folic acid deficiency
- Aplastic anemia
- Radiation therapy
- Bone marrow failure caused by infection or cancer
- Severe kidney disease; this may cause a low level of erythropoietin.
- Alcoholism
Reticulocyte, Absolute
