A complete blood count (CBC), also known as a complete blood cell count, full blood count (FBC), or full blood exam(FBE), is a blood panel requested by a doctor or other medical professional that gives information about the cells in a patient’s blood. A scientist or lab technician performs the requested testing and provides the requesting medical professional with the results of the CBC.
Blood counts of various types have been used for clinical purposes since the 19th century. Automated equipment to carry out complete blood counts was developed in the 1950s and 1960s.
The cells that circulate in the bloodstream are generally divided into three types: white blood cells (leukocytes ), red blood cells ( erythrocytes), and platelets (thrombocytes). Abnormally high or low counts may indicate the presence of many forms of disease, and hence blood counts are amongst the most commonly performed blood tests in medicine, as they can provide an overview of a patient’s general health status. A CBC is routinely performed during annual physical examinations in some jurisdictions
An example report format for a complete blood count. Note that test names, measurement units and reference ranges may vary between countries and laboratories. Patient results should always be interpreted using the units and reference ranges from the laboratory that produced the results.
Certain disease states are defined by an absolute increase or decrease in the number of a particular type of cell in the bloodstream.
|Type of Cell||Increase||Decrease|
|Red Blood Cells(RBC)||erythrocytosis or polycythemia||anemia or erythroblastopenia|
|White Blood Cells (WBC):||leukocytosis||leukopenia|
|Granulocytes||granulocytosis||granulocytopenia or agranulocytosis|
|All cell lines||–||pancytopenia|
Many disease states are heralded by changes in the blood count:
- Leukocytosis can be a sign of infection
- Thrombocytopenia can result from drug toxicity
- Pancytopenia is generally referred to as the result of decreased production from the bone marrow, and is a common complication of cancer chemotherapy.