CBC (Complete Blood Count) with Differential

What do the various levels in the CBC with Differential mean?

The CBC with differential panel is a summary of the “cellular” components of the blood, white cells, red cells, and platelets.

White blood cell count

White blood cells, also called “leukocytes,” are the cells that fight infection and protect the body by identifying and getting rid of invading organisms, viruses, dead or abnormal cells, or foreign bodies in the blood or tissues. Abnormally low leukocyte levels can indicate immune system problems. High white blood cell count can mean the body is stressed or fighting infection. Extremely high counts can indicate severe infection or leukemia.

Red blood cell count

Red blood cells carry oxygen to the body. Reduced numbers of red blood cells is referred to generally as “anemia.” Anemia can be caused by iron-deficiency and a host of other things. The count refers to the absolute number of red blood cells in a given volume of blood.


Hemoglobin levels refer to the amount of this oxygen-carrying molecule in a given volume of blood. Low hemoglobin usually means low iron. Iron is what makes blood red.


Hematocrit level is another way to measure the quantity of red blood cells. The Hematocrit number is the percent of red cells by volume in a given amount of blood.


MCV is the average size of the red cells. MCV can be altered in many disease states, either larger or smaller depending on what the problem is.


MCH / MCHC measures of the amount of hemoglobin in the red blood cells.


RDW refers to percent variation in size of red blood cells. In times of disease or damage to red blood cells, RDW variation will be high, and indicates often that the body is making a lot of new cells.

Platelet count

Platelets are the cells that make blood clot. Extremely low platelet counts are associated with some bleeding problems. Excessively high platelet counts can also cause problems.

Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils

Neutrophils, Lymphocytes, Monocytes, Eosinophils and Basophils are all specialized types of white blood cells. They are expressed on the lab sheet both as an absolute count and as a percent of the total white count. Minor variations of these counts from the “normal” range are common and of no concern. Abnormal counts or percentages of these sub-types are usually only meaningful when the total white count is grossly abnormal and one of these types of white cells predominates.