Basophils: What This White Blood Cell Count Means

Basophils are the least common white blood cells, but they have their own role in your immune defence. They contain histamine, among other substances, and are involved in allergic reactions and inflammatory processes.

This test measures how many basophils are present in your blood, as part of a complete blood count with differential. Because their share is normally very small, the value is often shown as both a percentage and an absolute number.

Due to the low normal count, a deviation only stands out once it is clear, and the result is always assessed together with the other blood values.

Basophils release substances such as histamine that play a role in allergic and inflammatory reactions. As a result, their number can give additional information alongside the other white blood cells.

A raised count (basophilia) is uncommon and can fit with prolonged allergic reactions, chronic inflammation or certain bone marrow conditions. Because a rise is rare, it usually calls for follow-up investigation.

A low basophil count, given the already low normal level, almost never has demonstrable meaning. The emphasis with this value is therefore on a rise in combination with other findings.

Basophils are measured automatically within a complete blood count with differential; you generally do not request them separately. They are part of the complete picture your doctor uses to assess your immune defence and blood production.

A raised count in particular can be a reason to look further, especially when other values in the blood count are also abnormal.

Your doctor always assesses the basophils in relation to the rest of the blood count and your symptoms, and suggests a repeat measurement or further investigation if needed.