Complete Blood Count (CBC)
Multiple cellular components of the blood, including Red Blood Cells (RBC), White Blood Cells (WBC), Platelets (PLT), Hemoglobin (Hgb), and Hematocrit (Hct).
A complete blood count, or CBC, is a group of blood tests that measure the number and size of the different cells in your blood. A CBC measures: Red blood cells , which carry oxygen from your lungs to the rest of your body. White blood cells , which fight infections and other diseases. There are five major types of white blood cells. A CBC test measures the total number of white cells in your blood. A different test called a CBC with differential measures the number of each type of these white blood cells. Platelets , which stop bleeding by helping your blood to clot. Hemoglobin , an iron-rich protein in red blood cells that carries oxygen from your lungs to the rest of your body. Hematocrit , the amount of whole blood that is made up of red blood cells. Mean corpuscular volume (MCV) , the average size of your red blood cells. Other names for a complete blood count: CBC, full blood count, blood cell count
Why is this test ordered? Your health care provider may have ordered a complete blood count as part of your checkup or to monitor your overall health. The test may also be used to: Help diagnose blood diseases , infections, immune system disorders, or other medical conditions Check for changes in an existing blood disorder
Reference Ranges
Adult reference interval: See individual markers (WBC, RBC, Hemoglobin, Hematocrit, Platelets)
| White Blood Cells (WBC) | 4,500 to 11,000 cells/mcL | Involved in fighting infections and mediating immune responses. |
| Red Blood Cells (RBC) - Male | 4.3 to 5.9 million cells/mcL | Erythrocytes responsible for oxygen transport throughout the body. |
| Red Blood Cells (RBC) - Female | 3.5 to 5.5 million cells/mcL | Oxygen transport cells. Values differ due to physiological characteristics. |
| Platelets (PLT) | 150,000 to 450,000 /mcL | Thrombocytes essential for blood clotting and vessel integrity. |
Reference intervals vary by performing laboratory, assay method, age and sex. Always interpret a result against the interval printed on the report from the laboratory that ran the test.
Clinical Interpretation
A CBC counts the cells in your blood. There are many reasons your levels may not be in the normal range . For example: Abnormal levels of red blood cells, hemoglobin, or hematocrit may be a sign of dehydration , anemia, heart disease , or too little iron in your body. A low white cell count may be a sign of an autoimmune disorder , bone marrow disorder , or cancer . A high white cell count may be a sign of an infection or a reaction to a medicine . If any of your levels are abnormal, it doesn't always mean you have a medical condition that needs treatment. Diet, activity level, medicines, having a menstrual period , not drinking enough water, and other factors can affect the results. Talk with your provider to learn what your results mean. Learn more about laboratory tests, reference ranges, and understanding results .
Related ICD-10 Codes
Clinical Protocol & Patient Advice
- 1
Fasting is typically not required for a standard CBC test unless performed alongside other fasting panels.
- 2
Inform your doctor of any blood thinners or steroids you are taking, as they can alter cellular concentrations.
- 3
Usually, no special preparation is necessary for a complete blood count. But if your provider ordered other tests on your blood sample, you may need to fast (not eat or drink) for several hours before the test. Your provider will let you know if there are any special instructions.
Usage Guidance
- Normal values vary slightly according to age, sex, and laboratory testing methodologies.
- An abnormal result does not immediately equal disease and must be interpreted within a full clinical context.
- Reference ranges vary by laboratory. Always discuss your specific results with a qualified healthcare professional.
Source: MedlinePlus, National Library of Medicine. View the original.