Lithium carbonate treatment in familial cyclic neutropenia.

A patient with previously documented cyclic neutropenia was followed for 48 days on no treatment. Blood counts obtained at 3-day intervals confirmed the presence of cyclic neutropenia with virtually complete disappearance of neutrophils at the nadir of cycles with a periodicity of 21 days. Lithium carbonate treatment was begun on day 49. Serum lithium levels remained in the therapeutic range throughout the study interval of 58 days. Periodicity and depth of neutropenia were not diminished during the study period.