Absolute counts are extremely important. If lymphocyte or other counts are reported as percentages of the total white blood count (wbc), the absolute values can be calculated as follows: Total wbc x % cell type reported / 100. This formula can be used for calculating the absolute lymphocyte count, absolute neutrophil count, etc.

By way of example, if the total white count reported is 25,000 and the percentage of lymphocytes reported is 80%, the calculation is as follows: 25,000 x 80 / 100. The result is an absolute lymphocyte count of 20,000.

If the total white blood count minus the total lymphocytes is less than 2000, the patient becomes increasingly at risk of infection. This is one of the reasons it is essential to monitor absolute counts, not percentages.