Neutropenia

Reference Range Neutropenia is currently defined as a neutrophil count less than 2.0 x 109/L, however a recent statistical analysis of 1.5 x 106 episodes across Sonic laboratories nationally, suggests that a lower limit of 1.7 or 1.8 x 109/L may be appropriate3,4. Physiological changes in neutrophil count can occur in an individual patient due to changes in neutrophil margination (exercise, stress) or total neutrophil numbers (steroid therapy, infection). The neutrophil count is also higher in pregnant women. Congenital Neutropenia Congenital causes of neutropenia include severe congenital neutropenia (SCN), cyclic neutropenia (CN), neutropenia associated with bone marrow failure syndromes, as well as benign ethnic neutropenia. Population studies show that approximately 5% of African Americans have a neutrophil count less than 1.5 x 109/L. Recent work has demonstrated that the cause of the neutropenia is due to an inherited polymorphism in the Duffy antigen5 on the red cell surface, common in African populations and protective against the P. Vivax malaria strain (see Figure 1).