White blood cells, also known as leukocytes, help protect the body against infections, bacteria, viruses and diseases. These essential part of the immune system are produced in the bone marrow and are present in the blood and lymph tissue. White blood cells (WBC) come in different types, and the blood normally contains a certain percentage for each type. This is what doctors check when they request tests that measure a person’s WBC count.
Why Do Doctors Check Your WBC Count?
The WBC count is usually included in a test that measures your complete blood count (CBC). A low white blood cell count or a high blood cell count may indicate an infection or an undiagnosed condition such as a blood disorder, an autoimmune diseases or an immune deficiency. The WBC count can help doctors detect and provide treatment for these potential conditions as well as help monitor the effectiveness of radiation treatment or chemotherapy for cancer patients.
What Is the Normal WBC Count?
People’s WBC count may vary depending on their age. Infants usually have a higher WBC count which gradually decreases as they get older. The table below shows the normal WBC ranges per microliter of blood (mcL).
Age rangeWBC count (per mcL of blood)Newborns9,000 to 30,000Children below 2 years old6,200 to 17,000Children over 2 years old and adults5,000 to 10,000Symptoms of an Abnormal WBC Count
An abnormal WBC count may either be lower or higher than the normal range. The common symptoms of a low WBC, also known as leukopenia, include body aches, chills, fever and headaches. If you have these symptoms, please schedule an appointment with your doctor and he/she may recommend a WBC count.
On the other hand, a high WBC count, also known as leukocytosis, usually doesn’t cause symptoms, although the underlying condition that’s causing it may show its own signs.
Risk Factors of an Abnormal WBC Count
A low WBC count may be triggered by the following factors or conditions:
- Autoimmune disorders
- Bone marrow damage or disorder
- Certain medications (i.e., antibiotics)
- Human immunodeficiency virus (HIV)
- Liver and spleen diseases
- Lupus
- Lymphoma
- Radiation therapy
- Severe infections
Meanwhile, a high WBC count may be triggered by the following factors or conditions:
- Asthma
- Certain allergies
- Certain infections (i.e., tuberculosis)
- Certain medications (i.e., corticosteroids)
- Exercise
- Inflammatory conditions (i.e., arthritis and bowel disease)
- Leukemia
- Pregnancy
- Smoking
- Stress
- Tissue damage
- Tumors in the bone marrow
How to Prepare for a WBC Count
First, you have to schedule an appointment with your doctor to get a test request and then schedule an appointment with the laboratory for blood extraction. Certain medications may either lower or increase your WBC count, so please let your physician know if you’re under medication. Some of the drugs that may interfere with your WBC count results are as follows:
- Antibiotics
- Anticonvulsants
- Antihistamines
- Chemotherapy medication
- Clozapine
- Corticosteroids
- Diuretics
- Heparin
- Quinidine
- Sulfonamides
Final Thoughts
If your laboratory test results show that you either have a low or high WBC count, your doctor may recommend a treatment plan and may also recheck your WBCs from time to time. But if your WBCs are within the normal range, great. Just keep doing things that can help boost your immune system and keep you healthy, such as eating fruits and vegetables, getting enough sleep, limiting your sugar intake, exercising regularly, managing your stress levels and staying hydrated. Have a great day ahead!
Blood cell counts give your doctor important clues about the state of your health before, during and after treatment. Blood counts alone can't determine whether you have a blood cancer, but they can alert your doctor if further testing is needed.
A complete blood count (CBC) is the number and types of cells circulating in your blood. Your CBC is measured using laboratory tests that require a small blood sample.
Blood is composed of several types of cells:
- Red cells, sometimes referred to as erythrocytes, pick up oxygen as blood passes through the lungs and release it to the cells in the body.
- White cells, sometimes referred to as leukocytes, help fight bacteria and viruses.
- Platelets help your blood clot in response to a cut or a wound.
A CBC also tests hemoglobin and hematocrit:
- Hemoglobin is a protein used by red cells to distribute oxygen to other tissues and cells in the body.
- Hematocrit refers to the amount of your blood that's occupied by red cells.
Normal Blood Counts
Normal blood counts fall within a range established by testing healthy men and women of all ages. The cell counts are compared to those of healthy individuals of similar age and sex. Nearly all lab reports include a "normal" range or high and low "values" to help you understand test results.
Normal Ranges of Blood Cell Counts for Healthy Adults and Children
Red Cells
per microliter (µL)
of bloodWhite Cells
per microliter (µL)
of bloodPlatelets
per microliter (µL) of bloodHematocrit1
% of blood composed of red cellsHemoglobin1
grams per deciliter (g/dL)Men
4.7 to 6.1 million
5,000 to 10,000
150,000 to 400,000
42 to 52
14 to 18
Women24.2 to 5.4 million
4,500 to 11,000
150,000 to 400,000
37 to 47
12 to 16
Children34.0 to 5.5 million
5,000 to 10,000
150,000 to 400,000
32 to 44
9.5 to 15.5
1The ratio of hematocrit to hemoglobin is about 3 to 1.
2Normal ranges for women who are pregnant differ from these ranges.
3These ranges are for children from infancy to adolescence; speak with your doctor to find out specific values for infants and young children.
White Cell Differential
Differential count, sometimes referred to as a "diff," is a breakdown of the different types of white cells. A white cell (WBC) differential also checks whether white cells appear normal. The five types of white cells and the approximate percentage they make up in the blood are:
- Neutrophils (55% to 70%)
- Band neutrophils (0% to 3%)
- Lymphocytes (20% to 40%)
- Monocytes (2% to 8%)
- Eosinophils (1% to 4%)
- Basophils (0.5% to 1%)
Until children are more than 4 years old, they have a higher percentage of lymphocytes in their blood than adults do.
How Blood Cancers Affect Blood Counts
Blood cancers can affect blood cell counts in a number of ways, either lowering or increasing measurements. If you're currently receiving cancer treatment such as chemotherapy, drug therapy or radiation, your blood counts will be affected. Blood counts usually return to normal after treatment is complete.
Should You Keep Track of Your Blood Counts?
Some people want to know the results of their blood count tests so they can take preventive measures to protect their health or to what's causing their symptoms. For example:
- If you have anemia as a result of low red cell counts, you'll understand why you have low energy levels or are unable to carry out everyday tasks.
- If you have low white cell counts and develop a fever, you'll know to contact your doctor promptly.
- If your platelet counts are too low, you can bleed or bruise easily, so you may choose to avoid activities that have a risk of injury.
Noncancerous Conditions
About 5 percent of healthy people will have test results outside of the "normal" range. If one or more of your blood cell counts is higher or lower than normal, your doctor will try to find out why. Many noncancerous conditions can contribute to low or high blood cell counts, such as those in the table below.