Diagnostic workup in front of an adult neutropenia.

Adult neutropenia, defined as a blood neutrophil count below 1.5 G/L, is a common condition. The most common cause of acute neutropenia is a drug-related reaction or an acute infectious disease. In chronic forms many etiologies are possible, sometimes poorly-defined, requiring precise explorations. The purpose of this article is to recall the required criteria for exploring neutropenia and to point out the algorithm of explorations in order to find the cause. Etiologies of acute and chronic forms are also detailed.