What is a complete blood count (CBC)?
A complete blood count is a laboratory blood test that measures the types of cells that circulate in your blood. The CBC can indicate or monitor health problems. Your healthcare provider may order a CBC to:
- Review your overall health
- Diagnose a medical condition
- Monitor an existing medical condition
- Monitor the treatment you are receiving for a current medical condition
What tests are included in a CBC?
A CBC will include the following values:
- White blood cell count (WBC) or leukocyte count - the total number of white blood cells in the sample
- WBC differential count - breakdown of the types of WBCs. This will include granulocytes, lymphocytes, monocytes, eosinophils, and basophils.
- Red blood cell count (RBC) or erythrocyte count - the total number of red blood cells in the sample.
- Hematocrit (HCT) - the percentage of the sample that was made of RBC.
- Hemoglobin (HGB) - the volume of the protein hemoglobin in the RBCs.
- Mean corpuscular volume (MCV) - the average volume of the RBC.
- Mean corpuscular hemoglobin (MCH) - the average amount of hemoglobin in the RBC.
- Mean corpuscular hemoglobin concentration (MCHC) - the average concentration of hemoglobin in the RBC.
- Red cell distribution width (RDW) - an indication of the size of the RBCs.
- Platelet count - the total number of platelets in the sample.
- Mean platelet volume (MPV) - an indication of the size of the platelets.
What are the five parts of a complete blood count (CBC)?
The five main parts of a CBC include:
- White blood cell count - the function of white blood cells is to fight infection.
- Red blood cell count - red blood cells carry oxygen for your body.
- Hemoglobin - hemoglobin is a protein of the RBC. It carries oxygen from the lungs and removes carbon dioxide as waste.
- Hematocrit - the percentage of the total blood count made of RBCs.
- Platelet count - platelets are essential for helping your blood to clot and stop bleeding.
What is a good complete blood count?
Normal values for a CBC are as follows:
- RBC - Male 4.35-5.65 trillion cells/L, female 3.92-5.13 trillion cells/L
- Hemoglobin - Male 13.2-16.6 grams/dL, female 11.6-15 grams/dL
- Hematocrit - Male 38.3-48.6%, female 35.5-44.9%
- White blood cell count 3.4-9.6 billion cells/L
- Platelet count - Male 135-317 billion/L, female 157-371 billion/L
What does it mean if your full blood count is abnormal?
An abnormal blood count may indicate several health conditions. Abnormalities in the RBC, hemoglobin, and hematocrit may indicate anemia when low. Higher than average values indicate conditions such as polycythemia vera or heart disease.
Low WBC levels may be caused by autoimmune disorders, bone marrow problems, or certain types of cancer. Some medications may also alter the WBC. High WBC levels indicate infection, inflammation, or bone marrow disease. The WBC level may also be affected by certain medicines.
Abnormal platelet counts indicate clotting disorders such as thrombocytopenia or thrombocytosis. Platelets may be affected by certain medications.
When your blood count has abnormalities, your healthcare provider may order additional testing and evaluation to determine the exact cause of the problem.
What diseases can a full blood count detect?
The CBC can detect many different conditions. Some of these include:
- Anemia
- Autoimmune disorders
- Bone marrow disorders
- Dehydration
- Infection
- Inflammation
- Leukemia
- Lymphoma
- Certain types of cancers
- Sickle cell disease
- Immune system disorders