Complete Blood Count (CBC) Explained: Red Cells, White Cells & Platelets in Palm Beach County, FL

What it involves

MedlinePlus describes a complete blood count, or CBC, as a group of blood tests that measure the number and size of the different cells in your blood. It is also called a full blood count or blood cell count. Because blood cells respond to infection, bleeding, iron levels, and hydration, the CBC is a broad first look that tells your provider whether to look further.

Who this is for

• Patients who had a CBC at a recent checkup and want the report explained in plain words
• Patients with tiredness, paleness, or frequent infections who want to know if blood counts could be involved
• Patients being monitored for a condition or treatment that can change blood cell counts
• Patients who were told a value was flagged high or low and are worried about what it means

What to expect

• A review of your symptoms, diet, medicines, and any earlier blood counts
• A blood draw from a vein in your arm, usually with no special preparation
• An explanation of each count, the flagged ones first
• A plan to repeat the test, or to add iron, vitamin, or other tests, if needed

What a CBC counts

MedlinePlus lists the parts of a CBC:

• Red blood cells, which carry oxygen from your lungs to the rest of your body
• White blood cells, which fight infections; a CBC with differential also counts each of the five types
• Platelets, which help the blood clot and stop bleeding
• Hemoglobin, the iron-rich protein in red cells that carries oxygen
• Hematocrit, the share of your blood made up of red cells, and MCV, the average size of a red cell

Why a provider orders it

MedlinePlus says a CBC is often part of a routine checkup. It is also used to monitor conditions or treatments that can affect blood cell counts, such as infections, anemia, immune system disorders, and blood cancers, and to help diagnose blood diseases or check for changes in an existing blood disorder. For most patients it is simply a baseline that is compared with the next one. A complete blood count with differential is one of the blood tests MedlinePlus lists for swollen lymph nodes, and the swollen lymph nodes guide explains the rest of that work-up. One common reason is a fever with no obvious cause, and the adult fever guide explains where a blood count fits among the tests MedlinePlus names for evaluating a fever.

What high or low red cell results can mean

MedlinePlus says abnormal levels of red blood cells, hemoglobin, or hematocrit may be a sign of dehydration, anemia, heart disease, or too little iron in the body. A flagged value does not pick one of those for you. Your provider uses your symptoms, your history, and often a follow-up test such as iron studies to decide which explanation fits. A low hemoglobin result is the usual first clue to anemia, and the anemia and low iron guide explains the follow-up iron tests and the causes a provider looks for.

What the white cell count can show

MedlinePlus says a high white cell count may be a sign of infection or a reaction to a medicine, while a low count may be a sign of an autoimmune disorder, a bone marrow disorder, or cancer. A mild bump during a cold or the flu is common, and the cold versus flu guide explains what to expect with a viral illness. Any low count is a reason to follow up, not to panic.

Why an abnormal result is not automatically a diagnosis

MedlinePlus is direct about this: if a level is abnormal, it does not always mean you have a condition that needs treatment. Diet, activity level, medicines, a menstrual period, and not drinking enough water can all affect the results. A repeat test after rehydrating or recovering from an illness is often the first step, which is why your provider may ask you to come back instead of ordering a long list of tests.

How a CBC fits with other blood work

A CBC is often drawn at the same time as other tests, such as thyroid results explained in the thyroid blood tests guide. MedlinePlus says that if other tests were ordered on the same sample, you may need to fast for several hours, even though a CBC alone usually needs no preparation. A yearly wellness visit is a common time for this blood work to be ordered. A blood count with a platelet count is one of the tests MedlinePlus says may be ordered when nosebleeds keep coming back, as described in the nosebleeds guide.

Sources

• MedlinePlus — Complete Blood Count (CBC)