Neutropenia (or granulocytopenia) is a depression of the absolute neutrophil count to less than 1,500/mm 3 . Leukopenia is a related term, denoting the depression of the total leukocyte count. Although neutropenia is the most frequent cause ofleukopenia, a marked lymphocytopenia can depress the total leukocyte count in the “penic” range with a normal neutrophil count. However, a severe leukopenia always implies neutropenia. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.