Basophils % (BASO%)

What is Basophils %?

Basophils % measures the percentage of basophils among your total white blood cells. Basophils are the rarest type of white blood cell, making up less than 1% of all circulating white blood cells under normal conditions. These cells play a key role in allergic reactions and inflammatory responses.

Why is it Tested?

Doctors order basophils % as part of a complete blood count with differential to evaluate immune system function and investigate allergic reactions, parasitic infections, or certain blood disorders. It’s particularly useful when assessing unexplained allergic symptoms or monitoring response to allergy treatments.

Normal Ranges

Reference ranges vary by lab, but general adult guidelines:

Adults: 0–1%

Normal basophils represent a very small fraction of total white blood cells, typically less than 1% in healthy individuals.

Reference ranges vary by authority. Track yours across multiple standards with automatic unit conversions in LabsVault.

What do Abnormal Results Mean?

Abnormal results are not a diagnosis. Always discuss your results with a qualified healthcare provider before making any medical decisions.

Low Basophils %

Very low or zero basophil percentages are typically normal, as these cells naturally represent less than 1% of white blood cells. Consistently absent basophils may occur with:

Acute stress or infection
Certain medications (corticosteroids)
Hyperthyroidism

High Basophils %

Elevated basophil percentages (basophilia) may indicate:

Allergic reactions or chronic allergies
Parasitic infections
Inflammatory bowel disease
Certain blood cancers (chronic myeloid leukemia)
Hypothyroidism

How to Track Over Time

Tracking basophil percentage trends helps identify developing allergic conditions or inflammatory processes before symptoms become severe. A gradual increase may signal emerging allergies, while sudden spikes warrant prompt medical evaluation to rule out serious underlying conditions.

Basophils %