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 in your blood. 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
Do I Need a Red Blood Cell Count?
According to the American
Association for Clinic Chemistry (AACC), the test is almost always a part
of a complete blood cell (CBC) test. A CBC test measures the number of all
types of components in the blood, including:
- red blood cells
- white blood cells
Your doctor may perform the test if they suspect you have a
condition that affects your RBCs or if there’s any sign that you have low blood
oxygen. The signs of low blood oxygen include:
- general fatigue
- nutritional deficiencies
A CBC test will often be part of a routine physical exam
because it’s a good 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.
Is the Test Performed?
An RBC count is a simple blood test performed by a healthcare
provider at your doctor’s office. They will draw blood from your vein, usually
on the inside of your elbow. The steps involved in the blood draw typically
- 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.
Should I Prepare for the Test?
There’s no special preparation required for this test. However,
you should tell your doctor if you’re taking medications, including any over-the-counter
drugs or supplements.
Talk to your doctor to find out if any other preparation is necessary.
Are the Risks of Taking the Test?
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 first enters your arm.
Do the Results Mean?
According to the Mayo
- The normal RBC range in males is 4.32 to 5.72 trillion
cells per liter.
- The normal RBC range in females is 3.90 to 5.03 trillion
cells per liter.
However, these ranges may vary slightly depending on the
laboratory or doctor.
Higher Than Normal
You have erythrocytosis if your RBC count is higher than
normal. This may be due to:
- cigarette smoking
- congenital heart disease
- renal cell carcinoma, which is a type of kidney
- pulmonary fibrosis
- polycythemia vera, which is a bone marrow
disease that causes overproduction of RBCs and is associated with a genetic
When you move to a higher altitude, your RBC count may
increase for several weeks because there’s less oxygen present in the air.
Certain drugs, such as gentamicin and methyldopa, can also
increase your RBC count. Be sure to tell your doctor about any medications you
Lower Than Normal
If the number of RBCs is lower than normal it may be caused
- bone marrow failure
- erythropoietin deficiency, which is the primary
cause of anemia in patients with chronic kidney disease
- hemolysis, or RBC destruction, due to
transfusion, blood vessel injury, or other causes
- leukemia, which is a cancer of the blood cells
- multiple myeloma, which is a cancer of the
plasma cells in bone marrow
- nutritional deficiencies, including deficiencies
in iron, copper, folate, and vitamins B-12 and B-6
Certain drugs can also lower your RBC count, especially:
- chemotherapy drugs
If I Have Abnormal Results?
Your doctor will discuss any abnormal results with you. A
high or low RBC count may help identify the cause of your symptoms. Depending
on your results and your situation, your doctor may need to order additional
tests or treatments.