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Red Blood Cell Count (RBC)

What is a red blood cell count?

A red blood cell count is a blood test that your doctor uses to find out how many red blood cells (RBCs) you have. It’s also known as an erythrocyte count.

The test is important because RBCs contain hemoglobin, which carries oxygen to your body’s tissues. The number of RBCs you have can affect how much oxygen your tissues receive. Your tissues need oxygen to function.

Symptoms of an abnormal count

If your RBC count is too high or too low, you could experience symptoms and complications.

If you have a low RBC count, symptoms could include:

If you have a high RBC count, you could experience symptoms such as:

  • fatigue
  • shortness of breath
  • joint pain
  • tenderness in the palms of the hands or soles of the feet
  • itching skin, particularly after a shower or bath
  • sleep disturbance

If you experience these symptoms your doctor can order an RBC count.

Why do I need an RBC count?

According to the American Association for Clinical Chemistry (AACC), the test is almost always a part of a complete blood count (CBC) test. A CBC test measures the number of all components in the blood, including:

  • red blood cells
  • white blood cells
  • hemoglobin
  • hematocrit
  • platelets

Your hematocrit is the volume of red blood cells in your body. A hematocrit test measures the ratio of RBCs in your blood.

Platelets are small cells that circulate in the blood and form blood clots that allow wounds to heal and prevent excessive bleeding.

Your doctor may order the test if they suspect you have a condition that affects your RBCs, or if you show symptoms of low blood oxygen. These could include:

A CBC test will often be part of a routine physical exam. It can be an indicator of your overall health. It may also be performed before a surgery.

If you have a diagnosed blood condition that may affect RBC count, or you’re taking any medications that affect your RBCs, your doctor may order the test to monitor your condition or treatment. Doctors can use CBC tests to monitor conditions like leukemia and infections of the blood.

How is the RBC count performed?

An RBC count is a simple blood test performed at your doctor’s office. You doctor will draw blood from your vein, usually on the inside of your elbow. The steps involved in the blood draw are:

  • The healthcare provider will clean the puncture site with an antiseptic.
  • They will wrap an elastic band around your upper arm to make your vein swell with blood.
  • They will gently insert a needle into your vein and collect the blood in an attached vial or tube.
  • They will then remove the needle and elastic band from your arm.
  • The healthcare provider will send your blood sample to a laboratory for analysis.

How should I prepare for the RBC count?

There’s typically no special preparation needed for this test. But you should tell your doctor if you’re taking medications. These include any over-the-counter (OTC) drugs or supplements.

Your doctor will be able to tell you about any other necessary precautions.

What are the risks of getting an RBC count?

As with any blood test, there’s a risk of bleeding, bruising, or infection at the puncture site. You may feel moderate pain or a sharp pricking sensation when the needle enters your arm.

What is the normal range for an RBC count?

According to the Leukemia & Lymphoma Society:

  • The normal RBC range for men is 4.7 to 6.1 million cells per microliter (mcL).
  • The normal RBC range for women who aren’t pregnant is 4.2 to 5.4 million mcL.
  • The normal RBC range for children is 4.0 to 5.5 million mcL.

These ranges may vary depending on the laboratory or doctor.

What does a higher than normal count mean?

You have erythrocytosis if your RBC count is higher than normal. This may be due to:

When you move to a higher altitude, your RBC count may increase for several weeks because there’s less oxygen in the air.

Certain drugs like gentamicin and methyldopa can increase your RBC count. Gentamicin is an antibiotic used to treat bacterial infections in the blood. Methyldopa is often used to treat high blood pressure. It works by relaxing the blood vessels to allow blood to flow more easily through the body. Be sure to tell your doctor about any medications you take.

A high RBC count may be a result of sleep apnea, pulmonary fibrosis, and other conditions that cause low oxygen levels in the blood. Performance-enhancing drugs like protein injections and anabolic steroids can also increase RBCs. Kidney disease and kidney cancers can lead to high RBC counts as well.

What does a lower than normal count mean?

If the number of RBCs is lower than normal, it may be caused by:

  • anemia
  • bone marrow failure
  • erythropoietin deficiency, which is the primary cause of anemia in patients with chronic kidney disease
  • hemolysis, or RBC destruction caused by transfusions and blood vessel injury
  • internal or external bleeding
  • leukemia
  • malnutrition
  • multiple myeloma, a cancer of the plasma cells in bone marrow
  • nutritional deficiencies, including deficiencies in iron, copper, folate, and vitamins B-6 and B-12
  • pregnancy
  • thyroid disorders

Certain drugs can also lower your RBC count, especially:

  • chemotherapy drugs
  • chloramphenicol, which treats bacterial infections
  • quinidine, which can treat irregular heartbeats
  • hydantoins, which are traditionally used to treat epilepsy and muscle spasms

Red blood cells and blood cancers

Blood cancers can affect the production and function of red blood cells. They can also result in unusual RBC levels.

Each type of blood cancer has a unique impact on RBC count. The three main types of blood cancer are:

  • leukemia, which impairs the bone marrow’s ability to produce platelets and red blood cells
  • lymphoma, which affects the white cells of the immune system
  • myeloma, which prevents normal production of antibodies

What if I have abnormal results?

Your doctor will discuss any abnormal results with you. Depending on the results, they may need to order additional tests.

These can include blood smears, where a film of your blood is examined under a microscope. Blood smears can help detect abnormalities in the blood cells (such as sickle cell anemia), white blood cell disorders such as leukemia, and bloodborne parasites like malaria.

A bone marrow biopsy can show how the different cells of your blood are made within your bone marrow. Diagnostic tests, such as ultrasounds or electrocardiograms, can look for conditions affecting the kidneys or heart.

Lifestyle changes

Lifestyle changes can affect your RBC count. Some of these changes include:

  • maintaining a healthy diet and avoiding vitamin deficiencies
  • exercising regularly, which requires the body to use up more oxygen
  • avoiding aspirin
  • avoiding smoking

You may be able to decrease your RBC with the following lifestyle changes:

  • reducing the amount of iron and red meat that you consume
  • drinking more water
  • avoiding diuretics, such as drinks containing caffeine or alcohol
  • quitting smoking

Dietary changes

Dietary changes can play a major part in home treatment by increasing or lowering your RBC count.

You may be able to increase your RBC with the following dietary changes:

  • adding iron-rich foods such as spinach to your diet
  • increasing copper in your diet with foods like shellfish, poultry, and nuts
  • getting more vitamin B-12 with foods like eggs, meats, and fortified cereals

Content licensed from:

Written by: Jacquelyn Cafasso and Ana Gotter
Medically reviewed on: Apr 06, 2017: Deborah Weatherspoon, PhD, RN, CRNA

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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