White Blood Cell Differential with Quantitative Count (Serum/Plasma Substance Concentration)

Why This Test Is Done

Doctors may order this test to evaluate symptoms like frequent infections, unexplained fevers, fatigue, or swelling. It’s also used to monitor conditions like leukemia, autoimmune diseases, or chronic infections. Sometimes, it’s part of routine check-ups or before starting certain treatments.

How the Test Works

A small blood sample is drawn, and the white blood cells are separated and analyzed. The test measures the proportion of each type of WBC and their total count. Some labs may also check for immature (band) neutrophils, which can signal infection or stress.

Common Conditions It Helps Identify

High or low counts of specific WBCs can point to infections (e.g., high neutrophils), immune disorders (e.g., low lymphocytes), or blood cancers (e.g., abnormal basophils). For example, a high eosinophil count might suggest allergies or parasitic infections, while low monocytes could indicate chronic illness.

What to Expect Before the Test

No special preparation is needed, but inform your doctor about any medications (especially steroids) or recent illnesses that might affect results. Avoid strenuous activity 24 hours before the test if possible, as it could temporarily shift WBC counts.