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RBC count

Erythrocyte count; Red blood cell count; Anemia - RBC count

 

An RBC count is a blood test that measures how many red blood cells (RBCs) you have.

RBCs contain hemoglobin , which carries oxygen. How much oxygen your body tissues get depends on how many RBCs you have and how well they work.

How the Test is Performed

 

A blood sample is needed.

 

How to Prepare for the Test

 

No special preparation is necessary.

 

How the Test will Feel

 

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

 

Why the Test is Performed

 

The RBC count is almost always part of a complete blood count ( CBC ) test.

The test can help diagnose different kinds of anemia (low number of RBCs) and other conditions affecting red blood cells.

Other conditions that may require an RBC count are:

  • Disease that damages kidney blood vessels ( Alport syndrome )
  • White blood cell cancer ( Waldenstrom macroglobulinemia )
  • Disorder in which red blood cells break down earlier than normal ( paroxysmal nocturnal hemoglobinuria )
  • Bone marrow disorder in which the marrow is replaced by scar tissue (myelofibrosis)

 

Normal Results

 

Normal RBC ranges are:

  • Male: 4.7 to 6.1 million cells per microliter (cells/mcL)
  • Female: 4.2 to 5.4 million cells/mcL

The ranges above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your health care provider about the meaning of your specific test results.

 

What Abnormal Results Mean

 

Higher than normal numbers of RBCs may be due to:

  • Cigarette smoking
  • Problem with heart's structure and function that is present at birth ( congenital heart disease )
  • Failure of the right side of the heart ( cor pulmonale )
  • Dehydration (for example, from severe diarrhea)
  • Kidney tumor (renal cell carcinoma)
  • Low blood oxygen level (hypoxia)
  • Scarring or thickening of the lungs ( pulmonary fibrosis )
  • Bone marrow disease that causes abnormal increase in RBCs ( polycythemia vera )

Your RBC count will increase for several weeks when you are in a higher altitude.

Drugs that can increase the RBC count include:

  • Gentamicin
  • Methyldopa

Lower-than-normal numbers of RBCs may be due to:

  • Anemia
  • Bleeding
  • Bone marrow failure (for example, from radiation, toxins, or tumor)
  • Deficiency of a hormone called erythropoietin (caused by kidney disease)
  • RBC destruction ( hemolysis ) due to transfusion, blood vessel injury, or other cause
  • Leukemia
  • Malnutrition
  • Bone marrow cancer called multiple myeloma
  • Too little iron, copper , folic acid, vitamin B6 , or vitamin B12 in the diet
  • Too much water in the body (overhydration)
  • Pregnancy

Drugs that can decrease the RBC count include:

  • Chemotherapy drugs
  • Chloramphenicol
  • Hydantoins
  • Quinidine

 

Risks

 

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:

  • Excessive bleeding
  • Fainting or feeling lightheaded
  • Hematoma (blood buildup under the skin)
  • Infection (a slight risk any time the skin is broken)

 

 

Open References

References

Bunn HF. Approach to the anemias. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 24th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 158.

Goljan EF. Red blood cell disorders. In: Goljan EF, ed. Rapid Review Pathology . 4th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 12.

 
  • Blood test

    Blood test - illustration

    Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.

    Blood test

    illustration

  • Formed elements of blood

    Formed elements of blood - illustration

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    Formed elements of blood

    illustration

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    High blood pressure tests - illustration

    Routine lab tests are recommended before beginning treatment of high blood pressure to determine organ or tissue damage or other risk factors. These lab tests include urinalysis, blood cell count, blood chemistry (potassium, sodium, creatinine, fasting glucose, total cholesterol and HDL cholesterol), and an ECG (electrocardiogram). Additional tests may be recommended based on your condition.

    High blood pressure tests

    illustration

    • Blood test

      Blood test - illustration

      Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.

      Blood test

      illustration

    • Formed elements of blood

      Formed elements of blood - illustration

      Blood transports oxygen and nutrients to body tissues and returns waste and carbon dioxide. Blood distributes nearly everything that is carried from one area in the body to another place within the body. For example, blood transports hormones from endocrine organs to their target organs and tissues. Blood helps maintain body temperature and normal pH levels in body tissues. The protective functions of blood include clot formation and the prevention of infection.

      Formed elements of blood

      illustration

    • High blood pressure tests

      High blood pressure tests - illustration

      Routine lab tests are recommended before beginning treatment of high blood pressure to determine organ or tissue damage or other risk factors. These lab tests include urinalysis, blood cell count, blood chemistry (potassium, sodium, creatinine, fasting glucose, total cholesterol and HDL cholesterol), and an ECG (electrocardiogram). Additional tests may be recommended based on your condition.

      High blood pressure tests

      illustration

    Self Care

     

      Tests for RBC count

       
       

      Review Date: 1/31/2016

      Reviewed By: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

      The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

       
       
       

       

       

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