Reticulocytes are immature red blood cells. A reticulocyte count is a test your doctor can use to measure the level of reticulocytes in your blood. It’s also known as a retic count, corrected reticulocyte count, or reticulocyte index.
A reticulocyte count can help your doctor learn if your bone marrow is producing enough red blood cells. If your red blood cell count is too low or too high, your body will try to achieve a better balance by producing and releasing more or less reticulocytes. Your doctor can tell whether your body is creating and releasing them properly by ordering a reticulocyte count.
A reticulocyte count can help your doctor make a diagnosis of a variety of conditions, such as anemia and bone marrow failure. They’ll likely order additional tests to develop their diagnosis.
Your doctor may recommend a reticulocyte count if they want to learn how your bone marrow is functioning, including production of enough red blood cells. They may also order a reticulocyte count to help diagnose and distinguish between different types of anemia.
To conduct a reticulocyte count, your doctor will need to collect a sample of your blood to send to a laboratory for testing.
Your doctor may ask you to take certain steps to prepare for drawing your blood. For example, they may ask you to fast for a specific period of time beforehand. They may ask you to avoid eating anything, drinking anything, or both. They also may ask you to avoid taking certain medications beforehand, such as blood thinners.
Ask your doctor if you should take any steps to prepare for your blood draw. Tell them if you have hemophilia, a history of fainting, or any other medical conditions beforehand. You should also tell them about any medications you’re taking, including prescription and over-the-counter drugs.
Your doctor, nurse, or technician will draw a sample of your blood for testing. They’ll likely take it from a vein in your inner elbow or the back of your hand.
First, they’ll sterilize the area with an antiseptic. Then, they’ll wrap a plastic band around your arm to apply pressure and help your vein swell with blood. They’ll insert a sterile needle into your vein and use it to collect a sample of your blood in an attached vial.
Once they’ve collected enough blood, they’ll remove the needle and untie the plastic band from your arm. Then they’ll clean the injection site and, if necessary, bandage it.
They’ll send the sample of your blood to a laboratory for testing. Your doctor will let you know when your test results are available.
Infants and young children
For infants or young children, the testing process may be different. Rather than use a needle to collect their blood, your child’s doctor may make a small cut in their skin. When the cut starts to bleed, they will use a test strip or slide to collect a small sample of your child’s blood. Then they’ll clean the area and, if necessary, bandage it.
Alternative testing methods
In some cases, you may not need to have your blood drawn. Instead, a simple finger prick may suffice. In this case, your doctor will prick your finger with a needle. When it starts to bleed, they’ll use a test strip or slide to collect a sample of your blood. Then they’ll clean the area and, if needed, bandage your finger.
Blood draws are common procedures. They’re generally safe for most people, but they do involve some risks.
You may experience mild to moderate pain from the needle prick. If your doctor, nurse, or technician has trouble collecting a blood sample, they may need to inject you with the needle several times. It’s common for the injection site to throb afterwards. Some bleeding and bruising are also common.
In rare cases, you may experience other side effects, such as:
- excessive bleeding at the puncture site
- accumulation of blood under your skin, known as a hematoma
- development of an infection where the needle pierced your skin
- inflammation of your vein, known as phlebitis
Your doctor can help you understand the potential benefits and risks of having your blood drawn. For most people, the potential benefits outweigh the risks.
Normal levels of reticulocytes vary, due to differing laboratory procedures and levels of hemoglobin in people’s blood. Your doctor may need to order additional tests to help interpret your reticulocyte count.
The results are reported as the percentage of reticulocytes divided by the total number of red blood cells times 100. The reference range, or healthy range, of the reticulocyte percentage in adults is 0.5 percent to 1.5 percent.
High reticulocyte levels could be a sign of:
- acute bleeding
- chronic blood loss
- hemolytic anemia
- erythroblastosis fetalis, also called hemolytic disease in a newborn, a potentially fatal blood disorder that affects some fetuses and newborns
- kidney disease
Low reticulocyte levels could indicate:
- iron deficiency anemia
- aplastic anemia
- folic acid deficiency
- vitamin B-12 deficiency
- bone marrow failure caused by drug toxicity, infection, or cancer
- kidney disease
- side effects from radiation therapy
Ask your doctor for more information about your test results. They can help you understand what your results mean. They can also recommend appropriate follow-up steps, which may include additional tests or treatments.