Basophils
Basophils are the white cells involved in allergic reactions and inflammation, and they are the rarest of the five types. Because there are so few of them, small changes are common and usually not a concern — a low or even zero result is normal. A result inside the range on your report is reassuring.
Standard CareWhat is basophils?
Basophils are white blood cells that are the least commonly found in your circulation, and they are mainly involved in allergic reactions. They release chemicals — such as histamine — that drive the body's response to allergens, so they play a part in the symptoms of allergies and in some kinds of inflammation. Your basophil count is measured in billions of cells per litre of blood (×10⁹/L) and is reported as part of the full blood count (FBC). Within the white cell count, each cell type is listed separately — the differential count — which reports neutrophils, lymphocytes, monocytes, eosinophils, and basophils both as an absolute number and as a percentage of the total. Because basophils normally make up only a tiny fraction of your white cells, many reports show a very low number as a matter of course. The count is read as part of the overall pattern rather than on its own.
Why is it tested?
Basophils are not usually tested on their own — they appear automatically as part of any full blood count. Your GP may order an FBC to look into a suspected infection, to investigate symptoms such as fatigue or persistent allergic-type symptoms, to monitor a known condition, or as part of a routine health check. White blood cells, including basophils, are part of your immune system; they help your body fight infection and other diseases, including cancer. Because basophils are one of five white cell types reported together, your GP reads the basophil count alongside the total white cell count and the rest of the differential — the full pattern says far more than this single, small number.
Reference range (Australia)
Reference intervals for basophils are analyser-specific and can vary between laboratories; because the numbers are very small, a low or zero result is common. The range printed on your own pathology report is the correct reference for your result.
Reference intervals vary between laboratories. Always use the range printed on your own report.
What your result means
A low basophil count is generally not significant. Because basophils are the least common white cell to begin with, a low or even undetectable number on a report is common and usually not a cause for concern on its own. Your GP reads a low basophil count in the context of the rest of your white cell counts rather than as a standalone finding.
A basophil count within the range on your report — typically a small number — suggests this part of your immune system is in its usual range. White blood cells protect your body continuously, so a normal result means your immune system is operating without a current major challenge. Your GP reads it together with the rest of the differential and your overall health picture.
A basophil count above the reference range is called basophilia. Because basophils are involved in allergic reactions, a raised count can be linked to allergic or inflammatory conditions. Less commonly, a persistently raised basophil count can be associated with certain bone marrow conditions, which is why your GP reads it alongside the rest of the full blood count rather than on its own. In practice, a mild rise in such a small number is far more often a passing reaction than a sign of anything serious. A single mildly raised basophil count is rarely significant by itself. Your GP will look at the whole FBC and your symptoms before drawing any conclusions, and can tell you whether it is worth a repeat count.
What can affect your result
Basophils make up such a small share of your white cells that day-to-day variation has a noticeable effect on the count, and a low or undetectable result is common and usually unremarkable. Allergic reactions and inflammation are the situations most associated with basophils, since these cells are mainly involved in allergic responses. As with other white cells, an inflammatory process or infection prompts the bone marrow to produce more white blood cells and release them into the circulation, with levels settling back to normal once the condition resolves. Because basophils are one of five reported white cell types, your GP always reads the count in the context of the total white cell count and the rest of the differential, rather than on its own. A persistently raised basophil count, particularly alongside changes in other cell lines, is the situation that prompts a closer look.
When to act
A basophil count slightly outside the reference range — particularly a low one — is rarely acted on by itself, because basophils are so few in number to begin with. If your result is out of range, your GP will read it alongside the rest of your full blood count and your symptoms. A persistently raised basophil count, or one accompanied by abnormalities in other cell lines, is the situation where your GP may look more closely with a repeat FBC over time or additional tests. Trends over time are more informative than a single reading, and the basophil count is best read in the context of your full FBC and your GP's clinical assessment. This page is general information and is not a substitute for advice from your GP.
Frequently asked questions
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