[Rational approach of leucocytosis in adults].

Several factors may influence the increased level of white blood cells (physical and/or emotional stimuli, infections, inflammations, drugs, toxins, etc.). The best approach to identify these disorders gets through a physical examination and a precise history. A particular attention should be focused on the onset of lymph nodes and/or splenomegaly. Among severe haematological disorders to take into consideration, we should exclude acute leukemias, chronic leukemias and myeloproliferative disorders.