A differential blood count gives the relative percentage of each type of white blood cell and also helps to reveal abnormal white blood cell populations (eg, blasts, immature granulocytes, and circulating lymphoma cells in the peripheral blood).
Reference ranges for differential white blood cell counts are as follows [1] :
Neutrophils - 2500-8000 per mm 3 (55-70%) Lymphocytes - 1000-4000 per mm 3 (20–40%) Monocytes - 100-700 per mm 3 (2–8%) Eosinophils - 50-500 per mm 3 (1–4%) Basophils - 25-100 per mm 3 (0.5-1%)Differential blood count gives relative percentage of each type of white blood cell and also helps reveal abnormal white blood cell populations (eg, blasts, immature granulocytes, or circulating lymphoma cells in the peripheral blood).
Differential blood count is also used along with leukocyte count (WBC) to generate an absolute value for each type of white blood cells (eg, absolute neutrophil count, absolute lymphocyte count, or absolute eosinophil count), which usually gives more meaningful information than the percentage of each, since relative percentage can be misleading. Expressing absolute values are also useful for monitoring (eg, monitoring neutropenia during chemotherapy or bone marrow transplantation). [2] Using absolute values, conditions such as neutropenia, neutrophilia, lymphopenia, lymphocytosis, monocytopenia, monocytosis, eosinophilia, and basophilia can be identified, whichcanhelp differential diagnosis of patient’s underlying disorders.
Differential blood count is not a part of complete blood count (CBC) but is interpreted together with CBC to help support or exclude a suspected diagnosis. For example, the presence of anemia along with thrombocytopenia with a low or high white blood cell count may suggest bone marrow involvement by leukemia.
Immature granulocytes (IGs) encompass immature cells of granulocytic lineages, including metamyelocytes, myelocytes, and promyelocytes, which are easily recognized morphologically and are reported by automated analyzer as IG altogether. [3] IG normally absent from peripheral blood.
Increased IG occurs accompanied by an increase in neutrophils in the following conditions: [2]