The white cell section of a blood count usually runs to eleven rows for five cell types. The repetition is deliberate: each type is reported two ways, and the two answer different questions.
What the differential is
MedlinePlus describes the base measurement — "White blood cells, which fight infections and other diseases. There are five major types of white blood cells" — and the extension: a "CBC with differential measures the number of each type of these white blood cells."
So the plain count is one number, and the differential breaks it into its five parts: neutrophils, lymphocytes, monocytes, eosinophils and basophils.
Percentages
The % rows say what share of the white cells each type makes up. They add to roughly 100, which
is the giveaway that they are shares rather than quantities.
A percentage is relative. It can move because the numerator changed, or because the total changed, and the percentage alone cannot distinguish the two.
Absolute counts
The ABSOLUTE rows say how many of each type there are in a volume of blood. Each is the total
white count multiplied by that type's percentage — so on most reports they are calculated rather
than separately measured.
An absolute count is independent of what the other cell types are doing.
Why both appear
Because a percentage can change without the thing it describes changing at all.
If the total white count falls while the number of lymphocytes stays exactly the same, the lymphocyte percentage rises — the same cells now make up a larger share of a smaller total. Nothing happened to the lymphocytes. Read on its own, the percentage column suggests otherwise.
This is why the absolute columns exist, and why they are generally the more stable of the two to follow across reports.
Reading them across a history
Compare like with like: percentage against percentage, absolute against absolute. Mixing them across reports produces movement that is arithmetic rather than biological.
If a report prints only percentages — some do — the absolute figure can be recovered from the total white count, which is on the same page. That reconstruction inherits the rounding of both inputs, so treat small movements accordingly.
