CBC explained
Understanding a complete blood count
The short version
A CBC (complete blood count) measures red blood cells, white blood cells, and platelets. It's often checked before and during chemotherapy to watch for effects on the bone marrow.
A (complete blood count) measures the cells that make up your blood. It's a routine test, often checked regularly during chemotherapy, since some treatments can temporarily lower blood cell counts.
- Red blood cells — carry oxygen; low levels can cause fatigue (anemia)
- White blood cells — help fight infection; a subtype called is often watched closely during chemotherapy
- Platelets — help blood clot; low levels can increase bruising or bleeding
Low counts and infection risk
If your white blood cell count is low, your care team may give you specific instructions about fever, avoiding crowds, or other precautions — follow those closely and call promptly if you develop a fever.
Questions you may want to ask
How often will my blood counts be checked?
What counts would delay or adjust my next treatment?