Basophils (%)
Basophils are the rarest type of white blood cell, and this figure shows what fraction of your total white blood cells they represent. They release histamine and other chemicals involved in allergic and inflammatory responses.
Basophils play a role in your body's reaction to allergens and parasites, and in longer-term inflammation. Because they are so uncommon, small shifts in the percentage can look dramatic without meaning much. This percentage is most useful alongside the absolute basophil count and the rest of the white cell differential.
A higher-than-usual basophil percentage can accompany allergic conditions, certain chronic inflammatory states, or, less commonly, some bone marrow disorders. Because basophils are so rare to begin with, a single elevated percentage often reflects normal variation rather than disease. Your clinician will look at the absolute count and the overall blood picture before drawing conclusions.
A low or even undetectable basophil percentage is common and generally not a cause for concern, since these cells are naturally scarce.
Most labs consider a small percentage typical, but reference ranges vary by laboratory and method. Use your own report's range and discuss any flagged result with your clinician.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.