White blood cells
What it measures, and what changes the number.
The white blood cell count is the total number of white cells (leukocytes) in a volume of blood. These cells are part of the immune system and include several types with different roles.
It is part of the complete blood count and is almost always read with the differential, which breaks the total into neutrophils, lymphocytes, monocytes, eosinophils and basophils, reported as absolute counts and percentages. The breakdown gives more detail than the total alone.
The count shifts through the day and rises temporarily with exercise, stress, smoking and recent meals, so timing can matter when comparing results. It is measured by automated analysers on an EDTA tube, and a delay before analysis or clumping of cells can affect the reading. Labs may print it as Leucocitos or, in Catalan, Leucòcits.
Often read alongside: Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils