Reticulocyte Count Normal Range and High or Low Results

What Reticulocytes Are

Reticulocytes are immature red blood cells that are still developing. The bone marrow creates these cells and releases them into the bloodstream. They mature within one to two days.

The main job of red blood cells is to carry oxygen from your lungs to every cell in your body. Bone marrow constantly produces new red cells to replace old cells as they die off.

Too few red blood cells and tissues may not get enough oxygen. Too many and there may be a risk of blood clots or other health concerns.

This laboratory test appears under several names on diagnostic reports. You may see it listed as a retic count, reticulocyte percent, reticulocyte index, corrected reticulocyte, or reticulocyte production index (RPI).

Reticulocyte Count Normal Range

According to the MedlinePlus Medical Encyclopedia, a normal reticulocyte count for healthy adults who are not anemic is 0.77% to 2.26%. Reference ranges differ between testing facilities because laboratories may use different measurement techniques or evaluate different blood samples.

Hemoglobin is the protein in red blood cells that carries oxygen. The expected reticulocyte range is higher when hemoglobin is low from bleeding or from red cells being destroyed. Compare your result with the range printed on your laboratory report.

High Reticulocyte Count Causes

A higher-than-normal reticulocyte count, known clinically as reticulocytosis, can mean your bone marrow is making more red blood cells than usual. According to MedlinePlus, an elevated result may mean:

• Hemolytic anemia, a condition where red blood cells are destroyed faster than the bone marrow can replace them.
• New or ongoing bleeding (hemorrhage), which prompts the marrow to make many more red cells to replace the loss.
• Hemolytic disease of the newborn (HDN).
• Kidney cysts or tumors that trigger increased production of the hormone erythropoietin.
• Pregnancy.

A result outside the normal range does not always mean anemia or another condition. For instance, moving to a higher altitude can cause a temporary rise in reticulocytes. The count should return to normal once your body gets used to the lower oxygen levels.

Low Reticulocyte Count Causes

A lower-than-normal reticulocyte count can mean that your bone marrow is not making enough red blood cells. MedlinePlus lists these possible causes of a low count:

• Iron deficiency anemia, which represents the most common form of anemia.
• Pernicious anemia, a type of megaloblastic anemia that can happen when the body does not get enough vitamin B12 and folate from the diet or cannot absorb them.
• Aplastic anemia, an uncommon disorder where the bone marrow cannot produce sufficient quantities of blood cells.
• Bone marrow failure, which can stem from infections, cancers, tumors, certain medications, or radiation therapy.
• Cirrhosis, which is scarring of the liver.
• Kidney disease, including chronic kidney disease that lowers the count through decreased amounts of erythropoietin.

Some medicines may raise or lower the count.

Why the Test Is Ordered

The test is most frequently used to diagnose specific types of anemia, which occurs when blood contains a lower-than-normal amount of red blood cells. It also allows providers to observe whether an ongoing anemia treatment is working properly.

The test may also be used to check bone marrow function after chemotherapy or a bone marrow transplant. Symptoms of anemia can also lead to testing: shortness of breath, weakness or fatigue, headache, dizziness, and arrhythmia (a problem with the rate or rhythm of the heartbeat).

Newborn infants may also receive a reticulocyte count to check for hemolytic disease of the newborn (HDN). This condition may happen when the mother's and baby's blood types do not match (Rh incompatibility), and the immune system attacks the baby's red blood cells. Rh incompatibility is usually tested for in routine prenatal screening, which helps prevent HDN through early treatment.

How the Test Is Done

A reticulocyte count requires a blood draw that usually takes less than five minutes to complete. A healthcare professional collects a blood sample from a vein in your arm using a small needle. You may feel a little sting.

No special preparation is required before this blood test. For newborn infants, the sample is taken using a heel poke rather than an arm vein.

The physical risks associated with this test are very low. You may experience slight pain or bruising at the needle site that usually goes away quickly.

What to Do with Your Result

Your provider reads the result together with your symptoms, medical history and other blood tests. If you have questions about your results or your child's results, talk to your health care provider. For other blood tests, see blood test results.

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