The diagnosis of anemia and its cause.

Screening patients for anemia and determining its cause is challenging and rewarding. Ordinarily, the cause can be readily diagnosed and treatment is available. A clinical approach to the diagnosis of anemia is presented. After clinically determining whether the anemia is due to decreased production of red blood cells, increased destruction, or loss of blood, initial laboratory investigations are specifically chosen to confirm the clinical impression or to answer basic clinical questions. The clinical features and initial laboratory findings should direct subsequent diagnostic and/or treatment approaches.