This is the first in a weekly series to help the average non-medical person understand the laboratory tests their physician orders, what kind of sample is required, what the test measure and what conditions can be diagnosed based on the results.
The Complete Blood Count or CBC is one of the most common, useful and important laboratory tests available in medical diagnoses. It is routinely ordered in annual physicals and Emergency room visits.
The CBC is an automated group of parameters of red blood cells, white blood cells and platelets used in detecting leukemias, anemias, blood loss and infections among other diseases and disorders. It is general examination of blood.
The test sample for a CBC is either a blood sample taken from the arm or fingerstick for adults and children, and heelstick for newborns.
The different parameters available in the typical CBC include:
• White Blood Cell count (WBC)
This is an actual count of the amount of white blood cells per volume of blood. This is useful for the detection of possible infection, neutropenia and other disorders.
• Red Blood Cell count (RBC)
This is an actual count of the amount of red blood cells per volume of blood. Low amounts of rbc’s could be an indicator of an anemia.
This is a protein that is contained inside the rbc. It measures the oxygen carrying capacity in the blood.
This represents the volume of rbc’s suspended in plasma in the person’s circulating blood. Both the hemoglobin and hematocrit are low in cases of blood loss.
• Mean Corpuscular Volume (MCV)
This is a measurement of rbc size. Depending on whether the MCV is high or low could indicate certain conditions such as anemias or thalassemias.
• Mean Corpuscular Hemoglobin (MCH)
This is a measure of the amount of hemoglobin in the individual rbc.
• Mean Corpuscular Hemoglobin Concentration (MCHC)
This is the amount of hemoglobin in circulating rbc’s regardless of the size of the rbc.
• Red Cell Distribution Width (RDW)
This is a calculation of the variation in the size of the rbc’s.
This is the amount of platelets in a given amount of blood. Platelets are important in blood clotting.
Your doctor will use the CBC as a screening test to see your general health status like in an annual physical. It may also be ordered to rule out infections, fatigue or other patient complaints. It is an important first test in the discovery of serious diseases like anemias and many other blood disorders.
What is a “normal” or reference range? It is a set of values of some measure that a physician or other health professional can use to interpret a set of results for a particular patient. You will see the reference ranges on the lab report next to your lab result. Your lab