What it is: A basophil count measures the number of basophils — a type of white blood cell involved in allergic responses — typically as part of a complete blood count (CBC) with differential.
Why it's ordered: Ordered alongside a CBC with differential when evaluating allergic reactions, unexplained inflammation, or certain blood disorders.
What it detects: Basophils release histamine during allergic reactions and heparin, which helps prevent excessive blood clotting. Elevated levels (basophilia) can suggest allergic conditions or, less commonly, myeloproliferative blood disorders; low levels are less clinically significant on their own.
Collection & prep: A standard blood draw from a vein in the arm, as part of a CBC with differential. No special preparation is needed.
Results:
High – basophilia; can be linked to allergic reactions or, rarely, myeloproliferative disorders
Normal – typically 0.5–1% of total white blood cells
Possible complications: Basophil counts are rarely abnormal in isolation and are usually interpreted together with the rest of the white blood cell differential rather than as a standalone diagnostic clue.
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