Basophils
Immune system healthAlso known as: BASO, Basos, baso's
Basophils release histamine during inflammatory and allergic reactions.
Reference range
Source: lab benchmark
Reference ranges may vary between labs and assays. Always interpret results with your healthcare provider.
Why this matters
Basophil levels can act as an early indicator of immune system activity. Elevated levels may signal allergies, chronic inflammation, or certain blood disorders, while low levels are usually not concerning. Lifestyle factors such as stress, sleep, and overall health can influence basophil counts. Monitoring helps assess allergic tendencies and inflammatory conditions.
How this connects to other biomarkers
- Elevated Basophils with persistent elevated WBC raise concern for a myeloproliferative disease (a chronic bone-marrow disorder — CML, polycythemia vera) — follow with a peripheral blood smear and JAK2 gene testing.
- Mild elevation can occur with allergic disease, underactive thyroid (high TSH), or chronic inflammation.
- Low Basophils are usually clinically silent.
How often should I test Basophils?
Most adults benefit from yearly basophil percentage testing as part of a CBC differential. Persistent elevation prompts your clinician's follow-up rather than a fixed retest cadence.
At baseline / for screening: Once every 12 months from age 30 as part of a CBC with differential.
Note: Basophil counts are very low and at the limit of analytical reliability on automated counters. Confirm unexpected results with a manual differential or repeat draw within 1 to 2 weeks; routine retest cadence isn't needed in healthy adults.
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