If you are having any symptoms or have any questions, please call 811 to speak with a registered nurse 24 hours a day.

Overview

A complete blood count (CBC) is a blood test that measures red blood cells, white blood cells, and blood platelets (cells that help your blood clot). It is one of the most common tests ordered by healthcare providers. A CBC can provide a quick snapshot of your overall health. If you’re not feeling well, this test can provide your healthcare provider with important information about what could be causing you to be sick.

Many times, your healthcare provider will order a CBC as part of a routine physical exam. The test results will provide your healthcare provider with a count of how many blood cells there are, and also describe their shape, size, and content. The results of a CBC can reveal a number of health conditions to your healthcare provider, from anemia to vitamin and mineral deficiencies.

Other reasons your doctor may order a CBC can include:

• If you are ill and have a fever or if they suspect any kind of infection.
• If you are tired or are losing weight without trying.
• If you have signs of other conditions, including general weakness, bruising, or bleeding.

If you have a condition that requires you to take daily medication, your healthcare provider may order a CBC regularly to make sure your blood counts remain consistent.

Path to improved health

When your healthcare provider orders a CBC, there are no special preparations you’ll need to take before the test. You are not required to fast (not eat or drink prior to the test), unless you are having other tests done at the same time that require it. However, you may want to wear a short-sleeved shirt or one that easily rolls up to expose the lower half of your arm.

You will most likely have to visit a blood collection facility to have the test done. This could be located in your healthcare provider’s office, at a hospital, or at an off-site location. At the facility, a phlebotomist (a person trained to draw blood for medical testing) will use a needle to collect a vial (sometimes more than one) of blood. The blood is most often collected from a vein on the inside of your elbow or on the back of your hand.

The CBC test takes only a few minutes.

The report will include the number of red blood cells and white blood cells. Red blood cells are important because they carry oxygen throughout your body. A low red blood cell count could mean that you have anemia. White blood cells are warriors that fight infections. A high white blood cell count could mean that you have an infection.

Following the CBC, your healthcare provider will evaluate the results. If your blood count is normal, you will may not need to do anything. Your healthcare provider will explain your results and advise if any follow-up is needed.

Things to consider

Having CBC lab work done poses very little risk to your health. However, anytime the skin is broken (even by a sterilized needle), there is always a slight risk of infection. You should also keep in mind that some blood may pool under the skin, causing a bruise after the test. If you are scared of needles, you may experience general anxiety about the test. Some people who are prone to fainting may faint during the test or can feel lightheaded. In rare cases, excessive bleeding can be a more serious response to the test.

If your numbers are too low or too high, your healthcare provider will discuss with you what that could mean and whether you’ll need additional tests. Abnormal test results could be an indication of a serious health problem or a simple one that can be remedied by eating better or taking supplements. These are some of the health problems that can be identified by a CBC:

• anemia (low iron)
• autoimmune disorders
• bone marrow problems
• certain types of cancer
• dehydration
• heart disease
• infection
• inflammation
• vitamin and mineral deficiencies