Neutrophil mobilization in lithium‐induced neutrophilia

Abstract Twenty patients on long‐term treatment with lithium who had persistently elevated neutrophil counts were challenged with adrenalin and hydrocortisone to measure their marginal and bone marrow granulocyte pools. Compared with normal controls the results suggest that the absolute numbers of granulocytes in each pool are not increased, although the percentage change is diminished because of the greater baseline values in the experimental group. These data suggest that lithium acts on granulopoiesis within the bone marrow, and are in keeping with the concept that the granulocyte reserve has a finite size. There is no apparent connection between lithium‐induced neutrophilia and either the therapeutic or unwanted effects of lithium.