Complete Blood Count (CBC): What Patients Should Know
A basophil count test measures the number of basophils, a type of white blood cell, in your blood to help evaluate your immune system and detect certain medical conditions.
{"Basophils are white blood cells that play a key role in allergic reactions and inflammation","This test is usually part of a complete blood count (CBC) with differential","Abnormal basophil levels may indicate allergies, infections, or blood disorders","The test requires a simple blood draw","Results are typically available within a few days"}
Key facts at a glance
- LOINC
- 705-4
- Short code
- BASOM
- Synonyms
- Basophils # Bld Manual
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA) vacuum blood collection tube; alternatively, EDTA microtainer for pediatric or capillary collections
- Units
- N/A
- Ref low
- 0
- Ref high
- 200
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–999 years
- Method
- manual-count
- CPT
- 85009
- SNOMED
- 303692001
- Specimen volume
- 3 mL whole blood for standard EDTA tube; 0.5-1 mL for pediatric microtainer
- Stability
- Specimen should be analyzed within 4 hours of collection at room temperature (18-25°C); slides for manual differential should be prepared within 2 hours of collection for optimal cell morphology preservation; refrigerated storage at 2-8°C extends stability up to 24 hours
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 1–4 hours
- Order
- routine
What is this test? A complete blood count, or CBC, is a common blood test that measures the different cells in your blood, including red blood cells, white blood cells, and platelets. These cells carry oxygen throughout your body, fight infection, and help your blood clot properly after an injury.
The basophil count test measures the number of basophils in your blood. Basophils are the least common type of white blood cell, making up less than 1% of all white blood cells in the body. Despite their small numbers, they play an important role in your immune system.
Why is it important? This test gives your doctor a broad picture of your overall health and can help detect many conditions, such as anemia, infections, and blood disorders, often before you notice any symptoms. It is also used to monitor an existing condition or to check how well a treatment, such as certain medications, is working for you.
Basophils are involved in defending your body against parasites and play a crucial role in allergic reactions. When you have an allergic reaction, basophils release histamine and other chemicals that cause symptoms like itching, swelling, and inflammation. This test helps doctors understand how your immune system is functioning.
How is the test performed? A trained healthcare professional will draw a small sample of blood, usually from a vein on the inside of your elbow or the back of your hand, using a thin needle. The entire procedure takes only a few minutes. You may feel a brief pinch or sting when the needle is inserted, and a small bandage will be placed over the site afterward.
A healthcare provider will draw a small sample of blood from a vein in your arm. The sample is then sent to a laboratory where technicians count the basophils under a microscope. This is called a manual differential count.
How to prepare: In most cases, no special preparation is needed, and you can eat and drink normally before the test. However, if your doctor has ordered other tests at the same time, such as a fasting blood sugar test, you may be asked to avoid eating or drinking for several hours beforehand. Be sure to tell your provider about any medications or supplements you take.
No special preparation is typically needed for this test. You may be asked to fast for several hours before the test if it's part of a larger blood panel. Always follow your healthcare provider's instructions.
Reference range
0-200 cells/mcL (0-0.2 x 10^9/L); typically expressed as 0-1% of total white blood cell countN/A
No special patient preparation required. Fasting is not necessary. Patients should inform their healthcare provider of any recent medications, as corticosteroids and other drugs may affect basophil counts.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated basophil levels (basophilia) may indicate: allergic reactions, asthma, parasitic infections, certain leukemias, myeloproliferative disorders, or inflammatory conditions. Low basophil levels (basopenia) are less common and may occur during pregnancy, hyperthyroidism, or as a side effect of certain medications like corticosteroids.
Basophil counts are rarely interpreted alone. Doctors consider them alongside other white blood cell counts and clinical symptoms to make a proper diagnosis. The absolute basophil count (the actual number of cells) is often more informative than the percentage.
Frequently asked questions
Does a high basophil count always mean I have a serious condition?
Can I change my basophil count through diet or lifestyle?
Is the basophil test painful?
How long does it take to get results?
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 16, 2026. · Read our editorial policy