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CBC Blood Test Result Explanation

A complete blood count (CBC) is a lab test used to analyze the number, size and shape of blood cells. Values measured by the CBC include red and white blood cell counts, hemoglobin concentration and platelet counts. Experienced hematologists confirm what automated analyzers report and detect blood diseases and abnormalities.

  1. Hematology

    • Hematology is the study of the blood. It used to be that a hematologist had only a microscope and experience to rely on when it came to analyzing blood. Modern hematology relies as much on automated equipment called cell counters as it does on human beings to detect blood diseases. Cell counters use radio frequency and electrical impedance to count cells and measure their size. Different chemicals are also used to analyze the chemical properties of blood.

    Complete Blood Count

    • The CBC gives the health care provider a picture of how many red blood cells, white blood cells and platelets are circulating in the patient. The CBC also helps to detect abnormalities. Once the blood sample is delivered to the laboratory, the hematologist first makes a blood smear on a glass slide to be viewed under the microscope later. The sample is then inserted into the analyzer. Using computerized algorithms, the analyzer may flag the sample for further analysis when it detects abnormalities in the cells. The hematologist may review the blood slide to confirm the findings of the analyzer. Normal CBC values vary from lab to lab.

    RBC Count

    • The red blood cell (RBC) count determines how many red blood cells are circulating in the body. Normal RBC counts range between 4.5 and 6.1 million cells per microliter (one millionth of a liter). The size and shape of the red blood cells are measured as mean corpuscular volume (MCV) and morphology. The mean hemoglobin concentration (MCH) measures the average amount of hemoglobin within each red blood cell.

    Hemoglobin and Hematocrit

    • Hemoglobin is responsible for carrying oxygen within red blood cells. The hematocrit refers to the proportion of red blood cells to plasma (the liquid portion of blood). Men usually have a hemoglobin concentration of between 14 to 18 grams per deciliter (tenth of a liter). Women have values of 12 to 16 grams per deciliter. Hematocrit values also vary between men and women, with men's hematocrit values between 42 percent and 52 percent; women's values are between 37 percent and 47 percent.

    WBC Count

    • White blood cells (WBC) are the cells responsible for defending the body against disease. The number of these in circulation depends on disease states, with higher numbers seen in disease than in health. A normal WBC count ranges from about 4,500 to 11,500 cells per microliter.

    Platelet Count

    • Platelets are cell fragments responsible for clotting. The number of platelets is indicative of the body's ability to form clots. A normal range of platelets is anywhere between 150,000 and 450,000 per milliliter (thousandth of a liter).

    Slide Reviews

    • When the analyzer is unable to properly identify an abnormality in blood cells, the hematologist will use the blood smear slide to visually identify cells. This is where experience is key since abnormalities in the cells may not be obvious to the inexperienced eye. A well-trained hematologist can identify anything from genetically-caused cell abnormalities to parasites in the blood.

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