The lack of clinical utility of white blood cell differential counts and blood morphology in elderly individuals with normal hematology profiles.

An investigation of 462 patients aged older than 65 years with normal hematology profiles revealed 105 individuals with unsuspected abnormalities in the white blood cell differential count, peripheral blood film, or platelet count. In only 8 patients would this information have resulted in additional patient testing or other changes in management. The availability of instrumentation providing an automated platelet count would have decreased the number of patients experiencing a change in management to 5. In no instance did physicians believe that an individual patient's clinical outcome would have been altered by a knowledge of the unexpected abnormalities or the anticipated management changes. In an ambulatory adult population with normal hematology profiles, there is limited clinical value in pursuing further studies, such as a white blood cell differential count or an examination of the red blood cell morphology.