What is a complete blood count

The complete blood count or CBC test is a test that evaluates the cells that circulate in your blood. Blood consists of three types of cells suspended in fluid called plasma: white blood cells, red blood cells and platelets. They are produced and mature primarily in the bone marrow and, under normal circumstances, are released into the bloodstream as needed.

The CBC is a very common test. Many people have a CBC performed when they have a routine health examination. If a person is healthy and has results that are within normal limits, then that person may not require another CBC until their health status changes or until their healthcare provider feels that it is necessary.

A CBC may be ordered when a person has any number of signs and symptoms that may be related to disorders that affect blood cells. When an individual has fatigue or weakness or has an infection, inflammation, bruising, or bleeding, a health practitioner may order a CBC to help diagnose the cause and/or determine its severity.

When a person has been diagnosed with a disease known to affect blood cells, a CBC will often be ordered on a regular basis to monitor their condition. Likewise, if someone is receiving treatment for a blood-related disorder, then a CBC may be performed frequently to determine if the treatment is effective.

Some therapies, such as chemotherapy, can affect bone marrow production of cells. Some medications can decrease white blood cell counts overall. A CBC may be ordered on a regular basis to monitor these drug treatments.

Red blood cell, white blood cells, and platelets are produced in the bone marrow and released into the peripheral blood. The primary function of the red blood cell is to deliver oxygen to tissues. White blood cells are key components of the immune system. Platelets play a vital role in blood clotting.

Mean corpuscular volume (MCV) is a measure of the size of the average red blood cell. Anemias are characterized as microcytic (MCV <80), macrocytic (MCV >100), or normocytic. The red cell distribution width (RDW) is a measure of the degree of variation in red blood cell size (anisocytosis). RDW (red cell distribution width) may be helpful in distinguishing between some anemias. For example, iron deficiency anemia is characterized by a high red cell distribution width (RDW), while thalassemia is characterized by a low red cell distribution width (RDW). These counts are used as clinical guides in the diagnosis or monitoring of many diseases.

Figure 1. Blood composition

Note: Blood consists of a liquid portion called plasma and a solid portion (the formed elements) that includes red blood cells, white blood cells, and platelets. When blood components are separated by centrifugation, the white blood cells and platelets form a thin layer, called the “buffy coat,” between the plasma and the red blood cells, which accounts for about 1% of the total blood volume. Blood cells and platelets can be seen under a light microscope when a blood sample is smeared onto a glass slide.

A CBC is typically performed using an automated instrument that measures various parameters, including counts of the cells that are present in a person’s sample of blood. The results of a CBC can provide information about not only the number of cell types but also can give an indication of the physical characteristics of some of the cells.

A standard CBC includes the following:

• Evaluation of white blood cells: white blood cell count; may or may not include a white blood cell differential
• Evaluation of red blood cells: red blood cell count, hemoglobin (Hb), hematocrit (Hct) and red blood cell indices, which includes mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and red cell distribution width (RDW). The red blood cell evaluation may or may not include reticulocyte count.
• Evaluation of platelets: platelet count; may or may not include mean platelet volume and/or platelet distribution width

Significant abnormalities in one or more of the blood cell populations can indicate the presence of one or more conditions. Typically other tests are performed to help determine the cause of abnormal results. Often, this requires visual confirmation by examining a blood smear under a microscope. A trained laboratorian can evaluate the appearance and physical characteristics of the blood cells, such as size, shape and color, noting any abnormalities that may be present. Any additional information is noted and reported to the healthcare provider. This information gives the health practitioner additional clues as to the cause of abnormal CBC results.

My CBC report includes a result for immature platelet fraction (IPF). What is it?

Immature platelet fraction (IPF) is the relative number of immature platelets (also called reticulated platelets) in the blood. Platelets are produced in the bone marrow and are normally not released into the bloodstream until they have matured. When platelet numbers in the blood are low (thrombocytopenia), it stimulates the bone marrow to produce platelets faster. When the need is great and when production cannot keep up with “demand,” then an increased number of immature platelets will be released into the bloodstream.

Immature platelet fraction test result would be one of the values reported when blood is evaluated using an automated hematology analyzer. The immature platelet fraction may be used to help a healthcare provider determine the likely cause of a person’s thrombocytopenia, that is, decrease in production by the bone marrow (IPF is low) versus increased loss of platelets in the blood (IPF is higher). Lab test results including platelet count and immature platelet fraction can also help determine if a person needs a platelet transfusion and help monitor bone marrow recovery, such as after a bone marrow transplant. Other uses are being studied and the test’s ultimate clinical utility has not yet been well determined.

My CBC report includes a result for reticulocyte hemoglobin. What is it?

The hemoglobin inside of reticulocytes can be measured and reported as either a mean reticulocyte hemoglobin content or a reticulocyte hemoglobin equivalent, depending upon the test method used. This test result would be one of the values reported when blood is evaluated using an automated hematology analyzer.

Reticulocytes are “young” red blood cells that are released by the bone marrow before they become fully mature. The amount of hemoglobin inside of reticulocytes can help determine if there has been enough iron available, to be incorporated into hemoglobin production and then into red blood cell production in the bone marrow, within the past few days. This makes the test useful in identifying functional iron deficiency in certain clinical conditions and in assessing iron deficiency anemia in children.

My CBC report includes a result for immature granulocytes. What are they?

Some automated hematology analyzers report the total number of immature granulocytes present in a person’s blood sample. Immature granulocytes are white blood cells that have not fully developed before being released from the bone marrow into the blood. They may include metamyelocytes, myelocytes, and promyelocytes. These cells are normally only present in the bone marrow because they are precursors of neutrophils, the predominant type of white cells in blood. The presence of immature granulocytes in the blood may occur in various diseases, such as infection or a blood cancer, and thus will often prompt further investigation, which may include additional laboratory testing.

Is there anything I can do to improve results of my CBC?

People who have a keen interest in their own health care frequently want to know what they can do to change their white blood cells, red blood cells, and platelets. Unlike “good” and “bad” cholesterol, cell populations are not generally affected by lifestyle changes unless the individual has an underlying deficiency (such as vitamin B12 or folate deficiency or iron deficiency). There is no way that a person can directly raise the number of his white blood cells or change the size or shape of his red blood cells. Addressing any underlying diseases or conditions and following a healthy lifestyle will help optimize your body’s cell production, and your body will take care of the rest.

If I have an abnormal result on my CBC, what other tests might my doctor order as follow up?

It depends on the results that are abnormal and the suspected cause as well as your medical history and findings from your physical examination. Your healthcare provider may request that a blood smear examination be done. Other general tests to check your health and to look for possible causes may include a comprehensive metabolic panel (CMP). A few other general examples include:

• Abnormal results for white blood cells may be followed by a culture of the affected area (e.g., blood culture, urine culture, sputum culture), a strep test or tests for viruses such as mononucleosis or Epstein-Barr virus (EBV). If inflammation is suspected, then a c-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) test may be done.
• Abnormal red blood cell results may prompt a reticulocyte count, iron studies, tests for vitamin B12 and folate, G6PD, or hemoglobinopathy evaluation to help make a diagnosis.
• An abnormal platelet count may be followed by tests that further evaluate platelets, such as platelet function tests or heparin-induced thrombocytopenia antibody. Additional tests may be done to check for bleeding disorders or excessive clotting disorders such as prothrombin time (PT), partial thromboplastin time (PTT), von Willebrand factor or coagulation factors.

When a serious condition such as leukemia, myelodysplasia or another bone marrow disorder is suspected, then a bone marrow biopsy and examination may be necessary. Numerous other tests specific for certain conditions may be needed to establish a diagnosis. Talk to your healthcare provider about the results of your CBC, whether additional tests are necessary, and why.

What does a CBC test for?

The three types of cells evaluated by the CBC include:

White Blood Cells

There are five different types of white blood cells, also called leukocytes, that the body uses to maintain a healthy state and to fight infections or other causes of injury. They are neutrophils, lymphocytes, basophils, eosinophils, and monocytes. They are present in the blood at relatively stable numbers. These numbers may temporarily shift higher or lower depending on what is going on in the body. For instance, an infection can stimulate the body to produce a higher number of neutrophils to fight off bacterial infection. With allergies, there may be an increased number of eosinophils. An increased number of lymphocytes may be produced with a viral infection. In certain disease states, such as leukemia, abnormal (immature or mature) white cells rapidly multiply, increasing the white blood cell count.

Red Blood Cells

Red blood cells, also called erythrocytes, are produced in the bone marrow and released into the bloodstream as they mature. They contain hemoglobin, a protein that transports oxygen throughout the body. The typical lifespan of an red blood cell is 120 days; thus the bone marrow must continually produce new red blood cells to replace those that age and disintegrate or are lost through bleeding. A number of conditions can affect the production of new red blood cells and/or their lifespan, in addition to those conditions that may result in significant bleeding.

The CBC determines the number of red blood cells and amount of hemoglobin present, the proportion of blood made up of red blood cells (hematocrit), and whether the population of red blood cells appears to be normal. Red blood cells normally are uniform with minimal variations in size and shape; however, significant variations can occur with conditions such as vitamin B12 and folate deficiencies, iron deficiency, and with a variety of other conditions. If the concentration of red blood cells and/or the amount of hemoglobin in the blood drops below normal, a person is said to have anemia and may have symptoms such as fatigue and weakness. Much less frequently, there may be too many red blood cells in the blood (erythrocytosis or polycythemia). In extreme cases, this can interfere with the flow of blood through the small veins and arteries.

Platelets

Platelets, also called thrombocytes, are special cell fragments that play an important role in normal blood clotting. A person who does not have enough platelets may be at an increased risk of excessive bleeding and bruising. An excess of platelets can cause excessive clotting or, if the platelets are not functioning properly, excessive bleeding. The CBC measures the number and size of platelets present.

How is CBC test used?

The complete blood count (CBC) is often used as a broad screening test to determine an individual’s general health status. It can be used to:

• Screen for a wide range of conditions and diseases
• Help diagnose various conditions, such as anemia, infection, inflammation, bleeding disorder or leukemia, to name just a few
• Monitor the condition and/or effectiveness of treatment after a diagnosis is established
• Monitor treatment that is known to affect blood cells, such as chemotherapy or radiation therapy

A CBC is a panel of tests that evaluates the three types of cells that circulate in the blood. A CBC includes the following:

• Evaluation of white blood cells, the cells that are part of the body’s defense system against infections and cancer and also play a role in allergies and inflammation:
  • White blood cell count is a count of the total number of white blood cells in a person’s sample of blood.
  • White blood cell differential may or may not be included as part of the panel of tests. It identifies and counts the number of the various types of white blood cells present. The five types include neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
• Evaluation of red blood cells, the cells that transport oxygen throughout the body:
  • Red blood cell count is a count of the actual number of red blood cells in a person’s sample of blood.
  • Hemoglobin measures the total amount of the oxygen-carrying protein in the blood, which generally reflects the number of red blood cells in the blood.
  • Hematocrit (Hct) measures the percentage of a person’s total blood volume that consists of red blood cells.
  • Red blood cell indices are calculations that provide information on the physical characteristics of the red blood cells:
    • Mean corpuscular volume (MCV) is a measurement of the average size of a single red blood cell.
    • Mean corpuscular hemoglobin (MCH) is a calculation of the average amount of hemoglobin inside a single red blood cell.
    • Mean corpuscular hemoglobin concentration (MCHC) is a calculation of the average concentration of hemoglobin inside a single red blood cell.
    • Red cell distribution width (RDW) is a calculation of the variation in the size of red blood cells.
• The CBC may also include reticulocyte count, which is a measurement of the absolute count or percentage of young red blood cells in blood.
• Evaluation of platelets, cell fragments that are vital for normal blood clotting:
  • The platelet count is the number of platelets in a person’s sample of blood.
  • Mean platelet volume may be reported with a CBC. It is a calculation of the average size of platelets.
  • Platelet distribution width may also be reported with a CBC. It reflects how uniform platelets are in size.

CBC test normal range

A health practitioner typically evaluates and interprets results from the components of the CBC together. Depending on the purpose of the test, a number of additional or follow-up tests may be ordered for further investigation.

RED BLOOD CELL COUNT (RBC)

Males:

• 0-14 days: 4.10-5.55 x 10(12)/L
• 15 days-4 weeks: 3.16-4.63 x 10(12)/L
• 5 weeks-7 weeks: 3.02-4.22 x 10(12)/L
• 8 weeks-5 months: 3.43-4.80 x 10(12)/L
• 6 months-23 months: 4.03-5.07 x 10(12)/L
• 24 months-35 months: 3.89-4.97 x 10(12)/L
• 3-5 years: 4.00-5.10 x 10(12)/L
• 6-10 years: 4.10-5.20 x 10(12)/L
• 11-14 years: 4.20-5.30 x 10(12)/L
• 15-17 years: 4.30-5.70 x 10(12)/L
• Adults: 4.35-5.65 x 10(12)/L

Females:

• 0-14 days: 4.12-5.74 x 10(12)/L
• 15 days-4 weeks: 3.32-4.80 x 10(12)/L
• 5 weeks-7 weeks: 2.93-3.87 x 10(12)/L
• 8 weeks-5 months: 3.45-4.75 x 10(12)/L
• 6 months-23 months: 3.97-5.01 x 10(12)/L
• 24 months-35 months: 3.84-4.92 x 10(12)/L
• 3-5 years: 4.00-5.10 x 10(12)/L
• 6-10 years: 4.10-5.20 x 10(12)/L
• 11-14 years: 4.10-5.10 x 10(12)/L
• 15-17 years: 3.80-5.00 x 10(12)/L
• Adults: 3.92-5.13 x 10(12)/L

HEMOGLOBIN

Males:

• 0-14 days: 13.9-19.1 g/dL
• 15 days-4 weeks: 10.0-15.3 g/dL
• 5 weeks-7 weeks: 8.9-12.7 g/dL
• 8 weeks-5 months: 9.6-12.4 g/dL
• 6 months-23 months: 10.1-12.5 g/dL
• 24 months-35 months: 10.2-12.7 g/dL
• 3-5 years: 11.4-14.3 g/dL
• 6-8 years: 11.5-14.3 g/dL
• 9-10 years: 11.8-14.7 g/dL
• 11-14 years: 12.4-15.7 g/dL
• 15-17 years: 13.3-16.9 g/dL
• Adults: 13.2-16.6 g/dL

Females:

• 0-14 days: 13.4-20.0 g/dL
• 15 days-4 weeks: 10.8-14.6 g/dL
• 5 weeks-7 weeks: 9.2-11.4 g/dL
• 8 weeks-5 months: 9.9-12.4 g/dL
• 6 months-35 months: 10.2-12.7 g/dL
• 3-5 years: 11.4-14.3 g/dL
• 6-8 years: 11.5-14.3 g/dL
• 9-10 years: 11.8-14.7 g/dL
• 11-17 years: 11.9-14.8 g/dL
• Adults: 11.6-15.0 g/dL

HEMATOCRIT

Males:

• 0-14 days: 39.8-53.6%
• 15 days-4 weeks: 30.5-45.0%
• 5 weeks-7 weeks: 26.8-37.5%
• 8 weeks-5 months: 28.6-37.2%
• 6 months-23 months: 30.8-37.8%
• 24 months-35 months: 31.0-37.7%
• 3-7 years: 34-42%
• 8-11 years: 35-43%
• 12-15 years: 38-47%
• 16-17 years: 40-50%
• Adults: 38.3-48.6%

Females:

• 0-14 days: 39.6-57.2%
• 15 days-4 weeks: 32.0-44.5%
• 5 weeks-7 weeks: 27.7-35.1%
• 8 weeks-5 months: 29.5-37.1%
• 6 months-23 months: 30.9-37.9%
• 24 months-35 months: 31.2-37.8%
• 3-7 years: 34-42%
• 8-17 years: 35-43%
• Adults: 35.5-44.9%

MEAN CORPUSCULAR VOLUME (MCV)

Males:

• 0-14 days: 91.3-103.1 fL
• 15 days-4 weeks: 89.4-99.7 fL
• 5 weeks-7 weeks: 84.3-94.2 fL
• 8 weeks-5 months: 74.1-87.5 fL
• 6 months-23 months: 69.5-81.7 fL
• 24 months-35 months: 71.3-84.0 fL
• 3-5 years: 77.2-89.5 fL
• 6-11 years: 77.8-91.1 fL
• 12-14 years: 79.9-93.0 fL
• 15-17 years: 82.5-98.0 fL
• Adults: 78.2-97.9 fL

Females:

• 0-14 days: 92.7-106.4 fL
• 15 days-4 weeks: 90.1-103.0 fL
• 5 weeks-7 weeks: 83.4-96.4 fL
• 8 weeks-5 months: 74.8-88.3 fL
• 6 months-23 months: 71.3-82.6 fL
• 24 months-35 months: 72.3-85.0 fL
• 3-5 years: 77.2-89.5 fL
• 6-11 years: 77.8-91.1 fL
• 12-14 years: 79.9-93.0 fL
• 15-17 years: 82.5-98.0 fL
• Adults: 78.2-97.9 3 fL

RED CELL DISTRIBUTION WIDTH (RDW)

Males:

• 0-14 days: 14.8-17.0%
• 15 days-4 weeks: 14.3-16.8%
• 5 weeks-7 weeks: 13.8-16.1%
• 8 weeks-5 months: 12.4-15.3%
• 6 months-23 months: 12.9-15.6%
• 24 months-35 months: 12.5-14.9%
• 3-5 years: 11.3-13.4%
• 6-17 years: 11.4-13.5%
• Adults: 11.8-14.5%

Females:

• 0-14 days: 14.6-17.3%
• 15 days-4 weeks: 14.4-16.2%
• 5 weeks-7 weeks: 13.6-15.8%
• 8 weeks-5 months: 12.2-14.3%
• 6 months-23 months: 12.7-15.1%
• 24 months-35 months: 12.4-14.9%
• 3-5 years: 11.3-13.4%
• 6-17 years: 11.4-13.5%
• Adults: 12.2-16.1%

WHITE BLOOD CELL COUNT (WBC)

Males:

• 0-14 days: 8.0-15.4 x 10(9)/L
• 15 days-4 weeks: 7.8-15.9 x 10(9)/L
• 5 weeks-7 weeks: 8.1-15.0 x 10(9)/L
• 8 weeks-5 months: 6.5-13.3 x 10(9)/L
• 6 months-23 months: 6.0-13.5 x 10(9)/L
• 24 months-35 months: 5.1-13.4 x 10(9)/L
• 3-5 years: 4.4-12.9 x 10(9)/L
• 6-17 years: 3.8-10.4 x 10(9)/L
• Adults: 3.4-9.6 x 10(9)/L

Females:

• 0-14 days: 8.2-14.6 x 10(9)/L
• 15 days-4 weeks: 8.4-14.4 x 10(9)/L
• 5 weeks-7 weeks: 7.1-14.7 x 10(9)/L
• 8 weeks-5 months: 6.0-13.3 x 10(9)/L
• 6 months-23 months: 6.5-13.0 x 10(9)/L
• 24 months-35 months: 4.9-13.2 x 10(9)/L
• 3-5 years: 4.4-12.9 x 10(9)/L
• 6-17 years: 3.8-10.4 x 10(9)/L
• Adults: 3.4-9.6 x 10(9)/L

PLATELETS

Males:

• 0-14 days: 218-419 x 10(9)/L
• 15 days-4 weeks: 248-586 x 10(9)/L
• 5 weeks-7 weeks: 229-562 x 10(9)/L
• 8 weeks-5 months: 244-529 x 10(9)/L
• 6 months-23 months: 206-445 x 10(9)/L
• 24 months-35 months: 202-403 x 10(9)/L
• 3-5 years: 187-445 x 10(9)/L
• 6-9 years: 187-400 x 10(9)/L
• 10-13 years: 177-381 x 10(9)/L
• 14-17 years: 139-320 x 10(9)/L
• Adults: 135-317 x 10(9)/L

Females:

• 0-14 days: 144-449 x 10(9)/L
• 15 days-4 weeks: 279-571 x 10(9)/L
• 5 weeks-7 weeks: 331-597 x 10(9)/L
• 8 weeks-5 months: 247-580 x 10(9)/L
• 6 months-23 months: 214-459 x 10(9)/L
• 24 months-35 months: 189-394 x 10(9)/L
• 3-5 years: 187-445 x 10(9)/L
• 6-9 years: 187-400 x 10(9)/L
• 10-13 years: 177-381 x 10(9)/L
• 14-17 years: 158-362 x 10(9)/L
• Adults: 157-371 x 10(9)/L

NEUTROPHILS

Males:

• 0-14 days: 1.60-6.06 x 10(9)/L
• 15 days-4 weeks: 1.18-5.45 x 10(9)/L
• 5 weeks-7 weeks: 0.83-4.23 x 10(9)/L
• 8 weeks-5 months: 0.97-5.45 x 10(9)/L
• 6 months-23 months: 1.19-7.21 x 10(9)/L
• 24 months-35 months: 1.54-7.92 x 10(9)/L
• 3-5 years: 1.60-7.80 x 10(9)/L
• 6-16 years: 1.40-6.10 x 10(9)/L
• 17 years: 1.80-7.20 x 10(9)/L
• Adults: 1.56-6.45 x 10(9)/L

Females:

• 0-14 days: 1.73-6.75 x 10(9)/L
• 15 days-4 weeks: 1.23-4.80 x 10(9)/L
• 5 weeks-7 weeks: 1.00-4.68 x 10(9)/L
• 8 weeks-5 months: 1.04-7.20 x 10(9)/L
• 6 months-23 months: 1.27-7.18 x 10(9)/L
• 24 months-35 months: 1.60-8.29 x 10(9)/L
• 3-5 years: 1.60-7.80 x 10(9)/L
• 6-14 years: 1.50-6.50 x 10(9)/L
• 15-17 years: 2.00-7.40 x 10(9)/L
• Adults: 1.56-6.45 x 10(9)/L

LYMPHOCYTES

Males:

• 0-14 days: 2.07-7.53 x 10(9)/L
• 15 days-4 weeks: 2.11-8.38 x 10(9)/L
• 5 weeks-7 weeks: 2.47-7.95 x 10(9)/L
• 8 weeks-5 months: 2.45-8.89 x 10(9)/L
• 6 months-23 months: 1.56-7.83 x 10(9)/L
• 24 months-35 months: 1.13-5.52 x 10(9)/L
• 3-5 years: 1.60-5.30 x 10(9)/L
• 6-11 years: 1.40-3.90 x 10(9)/L
• 12-17 years: 1.00-3.20 x 10(9)/L
• Adults: 0.95-3.07 x 10(9)/L

Females:

• 0-14 days: 1.75-8.00 x 10(9)/L
• 15 days-4 weeks: 2.42-8.20 x 10(9)/L
• 5 weeks-7 weeks: 2.29-9.14 x 10(9)/L
• 8 weeks-5 months: 2.14-8.99 x 10(9)/L
• 6 months-23 months: 1.52-8.09 x 10(9)/L
• 24 months-35 months: 1.25-5.77 x 10(9)/L
• 3-5 years: 1.60-5.30 x 10(9)/L
• 6-11 years: 1.40-3.90 x 10(9)/L
• 12-17 years: 1.00-3.20 x 10(9)/L
• Adults: 0.95-3.07 x 10(9)/L

MONOCYTES

Males:

• 0-14 days: 0.52-1.77 x 10(9)/L
• 15 days-4 weeks: 0.28-1.38 x 10(9)/L
• 5 weeks-7 weeks: 0.28-1.05 x 10(9)/L
• 8 weeks-5 months: 0.28-1.07 x 10(9)/L
• 6 months-23 months: 0.25-1.15 x 10(9)/L
• 24 months-35 months: 0.19-0.94 x 10(9)/L
• 3-5 years: 0.30-0.90 x 10(9)/L
• 6-17 years: 0.20-0.80 x 10(9)/L
• Adults: 0.26-0.81 x 10(9)/L

Females:

• 0-14 days: 0.57-1.72 x 10(9)/L
• 15 days-4 weeks: 0.42-1.21 x 10(9)/L
• 5 weeks-7 weeks: 0.28-1.21 x 10(9)/L
• 8 weeks-5 months: 0.24-1.17 x 10(9)/L
• 6 months-23 months: 0.26-1.08 x 10(9)/L
• 24 months-35 months: 0.24-0.92 x 10(9)/L
• 3-5 years: 0.30-0.90 x 10(9)/L
• 6-17 years: 0.20-0.80 x 10(9)/L
• Adults: 0.26-0.81 x 10(9)/L

EOSINOPHILS

Males:

• 0-14 days: 0.12-0.66 x 10(9)/L
• 15 days-4 weeks: 0.08-0.80 x 10(9)/L
• 5 weeks-7 weeks: 0.05-0.57 x 10(9)/L
• 8 weeks-5 months: 0.03-0.61 x 10(9)/L
• 6 months-23 months: 0.02-0.82 x 10(9)/L
• 24 months-35 months: 0.03-0.53 x 10(9)/L
• 3-11 years: 0.00-0.50 x 10(9)/L
• 12-17 years: 0.10-0.20 x 10(9)/L
• Adults: 0.03-0.48 x 10(9)/L

Females:

• 0-14 days: 0.09-0.64 x 10(9)/L
• 15 days-4 weeks: 0.06-0.75 x 10(9)/L
• 5 weeks-7 weeks: 0.04-0.63 x 10(9)/L
• 8 weeks-5 months: 0.02-0.74 x 10(9)/L
• 6 months-23 months: 0.02-0.58 x 10(9)/L
• 24 months-35 months: 0.03-0.46 x 10(9)/L
• 3-11 years: 0.00-0.50 x 10(9)/L
• 12-17 years: 0.10-0.20 x 10(9)/L
• Adults: 0.03-0.48 x 10(9)/L

BASOPHILS

Males:

• 0-14 days: 0.02-0.11 x 10(9)/L
• 15 days-7 weeks: 0.01-0.07 x 10(9)/L
• 8 weeks-35 months: 0.01-0.06 x 10(9)/L
• 3-17 years: 0.00-0.10 x 10(9)/L
• Adults: 0.01-0.08 x 10(9)/L

Females:

• 0-14 days: 0.02-0.07 x 10(9)/L
• 15 days-4 weeks: 0.01-0.06 x 10(9)/L
• 5 weeks-7 weeks: 0.01-0.05 x 10(9)/L
• 8 weeks-5 months: 0.01-0.07 x 10(9)/L
• 6 months-35 months: 0.01-0.06 x 10(9)/L
• 3-17 years: 0.00-0.10 x 10(9)/L
• Adults: 0.01-0.08 x 10(9)/L

Note: The reference ranges provided here represent a theoretical guideline that should not be used to interpret your test results. Some variation is likely between these numbers and the reference range reported by the lab that ran your test. Please consult your doctor for more information on reference ranges.

Reference ranges listed here are for adults older than 18 years old. They are not available for youths 0-18 years old due to wide variability.

Conventional Units are typically used for reporting results in U.S. labs. SI Units are used to report lab results outside of the U.S.

Many different conditions can result in increases or decreases in blood cell populations. Some of these conditions may require treatment, while others may resolve on their own.

Recent blood transfusions affect the results of the CBC.

Normal CBC values for babies and children are different from adults. The laboratory will supply the reference ranges for various age groups, and a health practitioner will take these into consideration when interpreting data.

The following tables briefly and generally explain what the result for each component of the CBC may mean.

Figure 2. Sample complete blood count (CBC) report

Components of the complete blood count

Table 1. White Blood Cell Evaluation

Test	Reference Range2	Examples of causes of a low count	Examples of causes of a high count
White Blood Cell Count (WBC)	Conventional Units1 4,500-11,000 white blood cells per microliter (mcL) SI Units1 4.5-11.0 x 109 per liter (L)	Known as leukopenia Bone marrow disorders or damage Autoimmune conditions Severe infections (sepsis) Lymphoma or other cancer that spread to the bone marrow Dietary deficiencies Diseases of immune system (e.g., HIV/AIDS)	Known as leukocytosis Infection, most commonly bacterial or viral Inflammation Leukemia, myeloproliferative neoplasms Allergies, asthma Tissue death (trauma, burns, heart attack) Intense exercise or severe stress
White Blood Cell Differential (Diff)	(Not always performed; may be done as part of or in follow up to CBC)
Absolute neutrophil count, % neutrophils (Neu, PMN, polys)	Conventional Units Percent (mean): 56% Absolute count (per microliter): 1800-7800 SI Units Mean number fraction: 0.56 Absolute count X 109 per liter: 1.8-7.8	Known as neutropenia Severe, overwhelming infection (sepsis) Autoimmune disorders Dietary deficiencies Reaction to drugs Immunodeficiency Myelodysplasia Bone marrow damage (e.g., chemotherapy, radiation therapy) Cancer that spreads to the bone marrow	Known as neutrophilia Acute bacterial infections Inflammation Trauma, heart attack, or burns Stress, rigorous exercise Certain leukemias (e.g., chronic myeloid leukemia) Cushing syndrome
Absolute lymphocyte count, % lymphocytes (Lymph)	Conventional Units Percent (mean) 34% Absolute count (per microliter): 1000-4800 SI Units Mean number fraction: 0.34 Absolute count X 109 per liter: 1.0-4.8	Known as lymphocytopenia Autoimmune disorders (e.g., lupus, rheumatoid arthritis) Infections (e.g., HIV, viral hepatitis, typhoid fever, influenza) Bone marrow damage (e.g., chemotherapy, radiation therapy) Corticosteroids	Known as lymphocytosis Acute viral infections (e.g., chicken pox, cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes, rubella) Certain bacterial infections (e.g., pertussis (whooping cough), tuberculosis (TB)) Toxoplasmosis Chronic inflammatory disorder (e.g., ulcerative colitis) Lymphocytic leukemia, lymphoma Stress (acute)
Absolute monocyte count, % monocytes (Mono)	Conventional Units Percent (mean) 4% Absolute count (per microliter) 0-800 SI Units Mean number fraction 0.04 Absolute count X 109 per liter 0-0.80	Usually, one low count is not medically significant.Repeated low counts can indicate: Bone marrow damage or failure Hairy cell leukemia Aplastic anemia	Chronic infections (e.g., tuberculosis, fungal infection) Infection within the heart (bacterial endocarditis) Collagen vascular diseases (e.g., lupus, scleroderma, rheumatoid arthritis, vasculitis) Monocytic or myelomonocytic leukemia (acute or chronic)
Absolute eosinophil count, % eosinophils (Eos)	Conventional Units Percent (mean) 2.7% Absolute count (per microliter) 0-450 SI Units Mean number fraction 0.027 Absolute count X 109 per liter 0-0.45	Numbers are normally low in the blood. One or an occasional low number is usually not medically significant	Asthma, allergies such as hay fever Drug reactions Parasitic infections Inflammatory disorders (celiac disease, inflammatory bowel disease) Some cancers, leukemias or lymphomas Addison disease
Absolute basophil count, % basophils (Baso)	Conventional Units Percent (mean) 0.3% Absolute count (per microliter) 0-200 SI Units Mean number fraction 0.030 Absolute count X 109 per liter 0-0.20	As with eosinophils, numbers are normally low in the blood; usually not medically significant	Rare allergic reactions (hives, food allergy) Inflammation (rheumatoid arthritis, ulcerative colitis) Some leukemias Uremia

[Sources ¹, ²]

Table 2. Red Blood Cell Evaluation

TEST	Reference Range2	Examples of causes of low result	Examples of causes of high result
Red Blood Cell Count (RBC)	Conventional Units Men: 4.5-5.9 x 106/microliter Women: 4.5-5.1 x 106 microliter SI Units Men: 4.5-5.9 x 1012/L Women: 4.1-5.1 x 1012/L	Known as anemia Acute or chronic bleeding RBC destruction (e.g., hemolytic anemia, etc.) Nutritional deficiency (e.g., iron deficiency, vitamin B12 or folate deficiency) Bone marrow disorders or damage Chronic inflammatory disease Chronic kidney disease	Known as polycythemia Dehydration Lung (pulmonary) disease Kidney or other tumor that produces excess erythropoietin Smoking Living at high altitude Genetic causes (altered oxygen sensing, abnormality in hemoglobin oxygen release) Polycythemia vera—a rare disease
Hemoglobin (Hb)	Conventional Units Men: 14-17.5 g/dL Women: 12.3-15.3 g/dL SI Units Men: 140-175 g/L Women: 123-153 g/L	Usually mirrors RBC results, provides added information	Usually mirrors RBC results
Hematocrit (Hct)	Conventional Units Men: 41.5-50.4% Women: 36.9-44.6% SI Units Men: 0.415-0.504 volume fraction Women: 0.369-0.446 volume fraction	Usually mirrors RBC results	Usually mirrors RBC results; most common cause is dehydration
RBC indices
MCV	Conventional Units 80-96 micrometer3 SI Units 80-96 fL	Indicates RBCs are smaller than normal (microcytic); caused by iron deficiency anemia or thalassemias, for example.	Indicates RBCs are larger than normal (macrocytic), for example in anemia caused by vitamin B12 or folate deficiency, myelodysplasia, liver disease, hypothyroidism
MCH	Conventional Units 27.5-33.2 pg SI Units 27.5-33.2 pg	Mirrors MCV results; small red cells would have a lower value.	Mirrors MCV results; macrocytic RBCs are large so tend to have a higher MCH.
MCHC	Conventional Units 33.4-35.5 g/dL SI Units 334-355 g/L	May be low when MCV is low; decreased MCHC values (hypochromia) are seen in conditions such as iron deficiency anemia and thalassemia.	Increased MCHC values (hyperchromia) are seen in conditions where the hemoglobin is more concentrated inside the red cells, such as autoimmune hemolytic anemia, in burn patients, and hereditary spherocytosis, a rare congenital disorder.
RDW (Not always reported)	RBC Distribution Width	Low value indicates uniformity in size of RBCs.	Indicates mixed population of small and large RBCs; young RBCs tend to be larger. For example, in iron deficiency anemia or pernicious anemia, there is high variation (anisocytosis) in RBC size (along with variation in shape – poikilocytosis), causing an increase in the RDW.
Reticulocyte Count (Not always done)	Conventional Units 0.5-1.5% or 25-75 x 103/microliter SI Units 0.005-0.015 number fraction or 25-75 x 109/L	In the setting of anemia, a low reticulocyte count indicates a condition is affecting the production of red blood cells, such as bone marrow disorder or damage, or a nutritional deficiency (iron, B12 or folate).	In the setting of anemia, a high reticulocyte count generally indicates peripheral cause, such as bleeding or hemolysis, or response to treatment (e.g., iron supplementation for iron deficiency anemia).

[Sources ¹, ²]

Table 3. Platelet Evaluation

Test	Reference Range2	Examples of causes of low result	Examples of causes of high result
Platelet Count (Plt)	Conventional Units 150-450 x 103/microliter SI Units 150-450 x 109/L	Known as thrombocytopenia: Viral infection (mononucleosis, measles, hepatitis) Rocky mountain spotted fever Platelet autoantibody Drugs (acetaminophen, quinidine, sulfa drugs) Cirrhosis Autoimmune disorders Sepsis Leukemia, lymphoma Myelodysplasia Chemo or radiation therapy	Know as thrombocytosis: Cancer (lung, gastrointestinal, breast, ovarian, lymphoma) Rheumatoid arthritis, inflammatory bowel disease, lupus Iron deficiency anemia Hemolytic anemia Myeloproliferative disorder (e.g., essential thrombocythemia)
MPV (Not always reported)	Mean Platelet Volume	Indicates average size of platelets is small; older platelets are generally smaller than younger ones and a low MPV may mean that a condition is affecting the production of platelets by the bone marrow.	Indicates a high number of larger, younger platelets in the blood; this may be due to the bone marrow producing and releasing platelets rapidly into circulation.
PDW (Not always reported)	Platelet Distribution Width	Indicates uniformity in size of platelets	Indicates increased variation in the size of the platelets, which may mean that a condition is present that is affecting platelets

[Sources ¹, ²]

1. Wintrobe’s Clinical Hematology. 12th ed. Greer J, Foerster J, Rodgers G, Paraskevas F, Glader B, Arber D, Means R, eds. Philadelphia, PA: Lippincott Williams & Wilkins: 2009.[↩][↩][↩]
2. Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. McPherson R, Pincus M, eds. Philadelphia, PA: Elsevier Saunders; 2011.[↩][↩][↩]