CBC Biomarker
Collection Type: Blood
Related System: CBC
Basophils are a type of white blood cell (granulocyte) produced in the bone marrow that normally make up a very small fraction of circulating leukocytes. They contain histamine, heparin and other mediators and participate in allergic responses, inflammation, and immune regulation. A basophil measurement on the CBC differential reports either the percent of white cells or the absolute basophil count. Abnormal basophil results can point to allergic conditions, chronic inflammation, parasitic infections, endocrine disorders (e.g., hypothyroidism), or bone‑marrow disorders such as myeloproliferative neoplasms. Symptoms prompting testing include unexplained allergic symptoms, persistent infection signs, unusual bruising/splenomegaly, or an abnormal routine CBC. Basophil counts are low across ages; significant rises are more concerning in older adults and minimally affected by sex.
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Q: What happens if basophils are high?
A: High basophils (basophilia) suggest active allergic or inflammatory responses, chronic infection, autoimmune disease, hypothyroidism, or a myeloproliferative disorder. Because basophils release histamine and heparin, elevations can accompany ongoing allergy symptoms and, rarely, affect clotting or bleeding. Persistent or markedly raised basophils warrant further evaluation (repeat CBC, allergy/infection workup and possibly bone marrow studies) to find the cause and guide treatment.
Q: What cancers are high in basophils?
A: Marked basophilia is most classically seen in chronic myeloid leukemia (CML). Elevated basophils also occur with other myeloproliferative neoplasms polycythemia vera, essential thrombocythemia and primary myelofibrosis and can be present in some acute leukemias and lymphomas (occasionally Hodgkin lymphoma). Reactive causes should also be considered; persistent unexplained basophilia warrants hematology evaluation.
Q: Is low basophil good?
A: Low basophil count (basopenia) is usually not harmful by itself. Basophils are a small type of white blood cell involved in allergy and inflammation; counts often fall during acute infection, stress, pregnancy, hyperthyroidism, or with steroid use. Isolated low basophils rarely indicate disease, but if persistent, unexpected, or with symptoms, repeat testing and discuss evaluation with your healthcare provider.
Q: What infection causes basophils?
A: Basophilia (increased basophils) is uncommon and usually signals allergic or chronic inflammatory conditions or myeloproliferative disorders such as chronic myeloid leukemia. Infections only occasionally cause basophil rises most often certain parasitic (helminth) infections and some viral illnesses. Because basophil elevation is nonspecific, clinical context and further blood tests are needed to find the underlying cause.
Q: What is the treatment for high basophils?
A: Treatment targets the underlying cause. For allergic or inflammatory basophilia: antihistamines, corticosteroids and identifying triggers. For reactive basophilia from infection or drugs: treat the infection or stop the offending medication. For persistent or clonal basophilia (myeloproliferative disorder): hematology referral, diagnostic workup and disease-specific therapy (tyrosine kinase inhibitors, cytoreductive agents like hydroxyurea, or JAK inhibitors). Regular monitoring is essential.
Q: Can leukemia cause high basophils?
A: Yes. Some leukemias—especially chronic myeloid leukemia and other myeloproliferative neoplasms—can cause basophilia (high basophil counts). Basophilia may also result from allergies, infections, or medications, so an isolated elevation is not diagnostic. Evaluation includes repeat CBC with differential, peripheral smear, molecular testing (eg, BCR‑ABL), and referral to a hematologist to identify the cause and guide treatment.