White Blood Cell (WBC) Count Test
This test measures the number of three types of white blood cells—basophils, eosinophils, and monocytes—in your blood using automated laboratory equipment.
{"Measures three types of white blood cells that help fight infections and regulate immune responses","Results are reported as absolute counts (number of cells per microliter of blood)","Abnormal levels may indicate allergies, infections, parasitic diseases, or blood disorders","The test requires a simple blood draw","Results are typically available within the same day"}
Key facts at a glance
- LOINC
- 32154-7
- Short code
- BASEMONO
- Synonyms
- Baso+Eos+Monos # Bld Auto
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA) vacuum blood collection tube; K2-EDTA or K3-EDTA anticoagulant tube
- Units
- N/A
- Ref low
- 215
- Ref high
- 1650
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- automated-count
- CPT
- 85025
- SNOMED
- 365642009
- Specimen volume
- 3-5 mL of whole blood (minimum 1 mL for pediatric samples)
- Stability
- Room temperature: up to 4 hours; Refrigerated (2-8°C): up to 24 hours. Cell morphology degrades rapidly beyond these timeframes; analysis should be performed as soon as possible after collection.
- Hemolysis max
- 100
- Lipemia max
- 200
- TAT
- 1–4 hours
- Order
- routine
What is a white blood cell count test?
This test measures the absolute counts of three specific types of white blood cells (leukocytes) in your blood: basophils, eosinophils, and monocytes. These cells are important components of your immune system and are counted using automated laboratory instruments that analyze a blood sample.
Understanding White Blood Cells and How They Work
White blood cells (WBCs) are key players in your immune system. Basophils are the least common and help mediate allergic reactions and inflammation. Eosinophils target parasites and play a role in allergic responses. Monocytes help digest bacteria, dead cells, and other debris, and also help coordinate immune responses.
How is the white blood cell test performed?
A healthcare professional will draw a small sample of blood from a vein in your arm. The sample is then placed in an automated analyzer that counts each type of white blood cell. No special preparation is typically needed, though your doctor may ask you to fast or avoid certain medications before the test.
What do the results of a white blood cell count mean?
Results are typically reported as absolute counts (e.g., cells per microliter of blood). Your doctor will interpret these results together with your overall health, symptoms, and other test results. Normal ranges can vary slightly between laboratories.
Reference range
Combined absolute count of basophils, eosinophils, and monocytes. Reference ranges vary by age: Adults typically have basophils 0-200/µL, eosinophils 15-500/µL, monocytes 200-950/µL, yielding a combined typical reference range of approximately 215-1650/µL.N/A
No special patient preparation required. Fasting is not necessary. Samples should ideally be collected when the patient is in a steady-state condition without recent acute infection or inflammatory episodes.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated eosinophil counts (eosinophilia) may indicate allergic reactions, parasitic infections, autoimmune conditions, or certain leukemias. Low eosinophil counts (eosinopenia) can occur during stress, acute infections, or with corticosteroid use.
Increased basophil counts (basophilia) may be seen in allergic reactions, chronic inflammation, certain infections, or blood disorders like chronic myeloid leukemia. Low basophil counts (basopenia) are less common but can occur with hyperthyroidism or during acute infections.
High monocyte counts (monocytosis) may indicate chronic infections, autoimmune disorders, or certain cancers. Low monocyte counts (monocytopenia) can occur with certain chemotherapy drugs, HIV infection, or bone marrow disorders.
This test is often part of a complete blood count (CBC) with differential, which provides a more comprehensive picture of your blood cell populations and overall health status.
Frequently asked questions
Do I need to fast before this test?
Is this test painful?
How long does it take to get results?
What can cause abnormal results?
Do I need to do anything special after the test?
Can this test diagnose specific diseases?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 15, 2026. · Read our editorial policy