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Basophil Manual

Complete Blood Count

Baso manualManual basophil count

Review status

Currently under review

Pending specialist review and validation.

What it shows

This test measures the number and proportion of basophils, a type of white blood cell involved in allergic responses and inflammation. A trained technologist examines a stained blood smear under a microscope and identifies basophils among other white cells.

It is usually performed as part of a complete blood count with differential, especially when an automated analyzer flags unusual results. Reporting may include an absolute basophil count and a percentage of total white blood cells.

Why it matters

Basophils can increase with allergic conditions, some chronic inflammatory states, and certain bone marrow disorders. They may decrease with acute stress or after specific medications. Your clinician may order a manual review to confirm or clarify automated results, to investigate symptoms such as persistent itching, hives, or wheezing, or to assess unexplained changes seen on a blood count.

Understanding your basophil results in context can help identify triggers for allergic symptoms, guide evaluation for infections or inflammatory diseases, and, in rare cases, suggest bone marrow conditions that need specialist assessment. Trends over time and related blood findings are often more informative than a single result.

Understanding your results

If your basophil count or percentage is higher than expected, causes can include allergies, chronic inflammation, thyroid disorders, or, less commonly, myeloproliferative diseases. Your clinician will interpret this alongside your symptoms, medications, and other blood results. Persistent or marked increases may prompt repeat testing, a peripheral smear review, or referral to a hematology specialist.

If your basophils are lower than expected, this is often not worrisome on its own and can be seen with stress, acute infection, or after corticosteroid use. Pregnancy can also lower basophil counts. If results do not fit your clinical picture, your clinician may repeat the test, review medications, or order targeted tests such as allergy evaluation, thyroid studies, or additional blood and bone marrow assessments when indicated.

Reference ranges

00.22 10⁹/L
All sexes
0 days – 150 years
02 %
All sexes
0 days – 150 years

Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.

Factors that could impact Basophil Manual

  • Recent medications

    Corticosteroids and other immunosuppressive drugs can lower basophil counts, while some chemotherapy or biologic agents may alter white cell distribution. Always share a full medication list, including over-the-counter and herbal products.

  • Allergy and asthma activity

    Active allergic rhinitis, eczema, urticaria, or asthma can be associated with higher basophil levels. Reporting recent flares helps your clinician interpret whether changes reflect current symptoms.

  • Acute illness and stress

    Recent infections, surgery, trauma, or significant physiologic stress can temporarily decrease basophil counts. Repeating the test after recovery often clarifies whether the change persists.

  • Pregnancy and hormones

    Pregnancy and some hormonal therapies can lower circulating basophils. Interpretation should consider pregnancy status and any estrogen or thyroid therapy.

  • Pre-analytic handling

    Delayed smear preparation, clotted or underfilled tubes, or poor smear quality can hinder accurate manual identification of cells. Proper collection and prompt slide preparation support reliable results.

  • Bone marrow and systemic diseases

    Myeloproliferative neoplasms, chronic inflammatory disorders, and thyroid disease can affect basophil production. Your clinician may correlate results with other blood indices and, if needed, pursue specialized testing.

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References

  1. McGill University Health Centre. (2015, July 06). Basophil Manual (Task CD 316022). Laboratory reference ranges.
  2. McGill University Health Centre. (2018, September 20). Basophil Manual (Task CD 856745). Laboratory reference ranges.
  3. International Council for Standardization in Haematology. (2015). Recommendations for peripheral blood film review and reporting. ICSH guideline.
  4. Clinical and Laboratory Standards Institute. (2007). Reference leukocyte differential count (manual methods), H20-A2.