Understanding Your Laboratory Blood Test: A Patient Guide to What It Is, Why It's Done, and What Results Mean
This test measures the percentage of basophils (a type of white blood cell) in your blood sample.
{"Basophils are a rare type of white blood cell that play a role in allergic reactions and immune responses","This test helps doctors evaluate your immune system and diagnose certain conditions","Normal basophil count is typically less than 1% of total white blood cells","Results may be affected by infections, allergies, or certain medications"}
Key facts at a glance
- LOINC
- 26445-7
- Short code
- BASO%
- Synonyms
- Basophils NFr Spec
- Category
- chemistry
- Sample
- serum
- Container
- EDTA (lavender-top) tube preferred; serum separator tube (SST) acceptable
- Units
- N/A
- Ref low
- 0.5
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Automated cell counting and differential analysis
- CPT
- 85025
- SNOMED
- 42735003
- Specimen volume
- 1-3 mL whole blood
- Stability
- Room temperature: 4 hours; Refrigerated (2-8°C): 24 hours; Smears should be prepared within 2 hours of collection
- Hemolysis max
- 100
- Lipemia max
- 500
- Icterus max
- 10
- TAT
- 1–4 hours
- Order
- routine
What is this test? A laboratory blood test is a routine procedure in which a small sample of your blood is drawn and analyzed to measure blood cells, chemicals, proteins, and other substances that show how well your body is functioning.
The Basophil/White Blood Cell 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. They play an important role in your body's immune system, particularly in fighting parasites and in allergic reactions.
Why is this test performed? This test is performed to check your overall health, help diagnose a wide range of conditions such as infections, anemia, or organ problems, monitor an existing condition, or see how well a treatment or medication is working over time.
This test is usually part of a complete blood count (CBC) with differential. It helps your doctor understand how your immune system is functioning and can aid in diagnosing various conditions such as allergic reactions, infections, inflammatory diseases, and certain blood disorders.
How is the test done? A healthcare professional cleans your skin, wraps a band around your upper arm, and inserts a small needle into a vein, usually in your arm, to collect a blood sample into one or more tubes. The sample is then sent to a laboratory, and the needle site is covered with a bandage.
A healthcare professional will collect a blood sample from a vein in your arm. The sample is then sent to a laboratory where it is analyzed to determine the percentage of basophils relative to other white blood cells.
What do the results mean? Your results are compared with reference ranges that show the typical levels seen in healthy people. Values that are higher or lower than normal can point to a condition that needs attention, but only your doctor can interpret them correctly alongside your symptoms, history, and other tests.
Results are typically reported as a percentage. Normal basophil count is usually less than 1% of total white blood cells. Your doctor will interpret your results based on your overall health and other test findings.
Reference range
0.5-1.0% of total leukocytes; absolute count 0-200 cells/μLN/A
No special patient preparation required. Specimen should be collected by trained phlebotomist to avoid hemolysis or clotting.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated basophil levels (basophilia) may indicate: allergic reactions, parasitic infections, chronic inflammation, certain leukemias, or hypothyroidism. Decreased basophil levels (basopenia) may be seen in acute infections, hyperthyroidism, or during acute illness. This test helps healthcare providers diagnose and monitor these conditions.
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 affect my basophil count?
Sources
- 1
- 2
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