A complete blood count, also known as a CBC, is a common blood test. The test measures the number of white cells and the number of red cells in a measure of blood. The test also measures the amount of hemoglobin in the red cells, the ratio of red cells (known as the hematocrit) and the number of platelets. Physicians use this test along with history, examination and other laboratory tests to evaluate symptoms or as part of an annual physical to identify or rule out potential illnesses. No special preparation is needed---foods and activity do not directly affect the results.
Step 1
Compare the numerical results to the listed normal ranges. Remember that normal ranges can vary between laboratories, and actual results are only part of the over picture of your health.
Step 2
Notice any abnormal results. A high number of white blood cells could suggest an infection, while a low number of red cells could suggest anemia. Both results could have many different causes. Medline Plus Medical Encyclopedia notes the following values as a guide to normal ranges: wbc (white blood cells) 4500 to 10000 cells per microliter and RBC (red blood cells) 4.7 to 6.1 million cells per microliter for men and 4.2 to 5.4 million cells per microliter for women.
Step 3
Discuss the results with your physician. Your doctor may decide to order follow-up testing in order to determine the exact cause of an abnormality. A common addition to a CBC is a differential. The differential provides a breakdown by percentage of the different types of white blood cells withing the sample. This additional information is often helpful in determining a diagnosis.
Step 4
Disclose any symptoms you may have been experiencing as this may help your doctor interpret the results. For example, a low hematocrit or low hemoglobin level may help explain fatigue, as they point to anemia. Medline Plus Medical Encyclopedia notes that hematocrit normals vary with altitude and average 40.7 to 50.3 percent for men and 36.1 to 44.3 percent for women.
Step 5
Consider that medication may be the cause of present abnormalities. Sometimes discovery of internal bleeding caused by medications may occur through the presence of a low platelet count or low hematocrit level. Patients who regular take aspirin or prescription anti-inflammatory medications often have this test performed on a regular basis as these medications sometimes affect the blood's ability to clot.
