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Reticulocyte Count

Test Overview

A reticulocyte count is a blood test that measures how fast red blood cells called reticulocytes are made by the bone marrow and released into the blood. Reticulocytes are in the blood for about 2 days before developing into mature red blood cells.

The reticulocyte count rises when there is a lot of blood loss or in certain diseases in which red blood cells are destroyed prematurely, such as hemolytic anemia. Also, being at high altitudes may cause reticulocyte counts to rise, to help you adjust to the lower oxygen levels at high altitudes.

Why It Is Done

A reticulocyte count is done to:

  • See whether anemia is caused by fewer red blood cells being made or by a greater loss of red blood cells.
  • Check how well bone marrow is working to make red blood cells.
  • Check to see if treatment for anemia is working. For example, a higher reticulocyte count means that iron replacement treatment or other treatment to reverse the anemia is working.

How To Prepare

You do not need to do anything before you have this test.

How It Is Done

The health professional drawing blood will:

  • Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
  • Clean the needle site with alcohol.
  • Put the needle into the vein. More than one needle stick may be needed.
  • Attach a tube to the needle to fill it with blood.
  • Remove the band from your arm when enough blood is collected.
  • Put a gauze pad or cotton ball over the needle site as the needle is removed.
  • Put pressure on the site and then put on a bandage.

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Risks

There is very little chance of a problem from having a blood sample taken from a vein.

  • You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
  • In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.

Results

A reticulocyte count is a blood test that measures how fast red blood cells called reticulocytes are made by the bone marrow and released into the blood.

Normal

The reticulocyte count is given as the percentage of red blood cells that are reticulocytes (the number of reticulocytes divided by the total number of red blood cells, multiplied by 100).

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Results are ready in 1 day.

Reticulocyte countfootnote 1

Adults:

0.5%–1.5%

Newborns:

3%–6%

High values

Low values

  • A low reticulocyte count may mean fewer red blood cells are being made by the bone marrow. This can be caused by aplastic anemia or other types of anemia, such as iron deficiency anemia.
  • A low reticulocyte count can also be caused by exposure to radiation, a long-term (chronic) infection, or by certain medicines that damage the bone marrow.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Taking certain medicines. Medicines that affect the results include ones used for Parkinson's disease, rheumatoid arthritis, fevers, malaria, and cancer chemotherapy.
  • Getting radiation therapy.
  • Taking sulfonamide antibiotics (such as Septra).
  • Being pregnant.
  • Having a recent blood transfusion.

References

Citations

  1. Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

Credits

Current as of: April 30, 2024

Author: Ignite Healthwise, LLC Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

Current as of: April 30, 2024

Author: Ignite Healthwise, LLC Staff

Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

Dear patient

I am excited to announce that I will be relocating my practice to Houston Methodist DeBakey Cardiology Associates. Starting November 4, 2024, my new address will be:

Houston Methodist DeBakey Cardiology Associates
6550 Fannin St.
Smith Tower, Suite 1901
Houston, TX 77030

Please note that my phone number and fax number will also change to the following:
24-Hour Telephone: 713-441-1100
Fax: 713-790-2643
Clinical Support Telephone (M-F, 8-5): 713-441-3515

I am excited about caring for you in my new office and hope you will make the transition with me. I will also continue to refill your medications as I have in the past. To assist, please provide your pharmacy with my new contact information.

Please consider checking your prescription refills to verify that you have enough medication on hand to last you until your next visit. Please note that your medical records will remain at my former office until you authorize their transfer. If you choose for me to continue providing your medical care, please complete and sign the enclosed “Authorization for Release of Medical Records” form and fax it to 713-790-2643. Once we receive your authorization, we will be happy to process the request for you.

Thank you for entrusting me with your medical care. My new team and I are dedicated to making this transition as seamless as possible. For help scheduling an appointment and transitioning your care, please call my new office number above.

I look forward to continuing your care at my new location.

Sincerely,
Gopi A. Shah, MD

Dear patient

Dr. Albert Raizner, Dr. Michael Raizner, and Dr. Mohamed El-Beheary are excited to announce that our practice, Houston Cardiovascular Associates, will merge with Houston Cardiovascular Associates on November 1, 2024.

Our new offices are similarly located in Houston, near the Texas Medical Center and in Sugar Land. Our in-hospital care will continue at Houston Methodist Hospital in the Texas Medical Center and Houston Methodist Sugar Land Hospital. Importantly, our new offices expand our services with state-of-the-art equipment and amenities. Our core values will always be, as they began over 40 years ago when Dr. Albert Raizner founded HCA:

Integrity – Compassion – Accountability

Our new address and contact information are:

Your medical records are confidential and remain available at our new locations. We consider it a privilege to serve as your cardiologists and look forward to your continuing with us. However, should you desire to transfer to another physician, you may request a copy of your records by contacting us at our new addresses and phone numbers listed above.

We thank you for your trust and loyalty. As always, we will continue to be here to take care of you. Please do not hesitate to contact us if you have any questions or concerns.

Sincerely,

Dr. Albert Raizner,
Dr. Michael Raizner,
Dr. Mohamed El-Beheary