Anemia, a clinical finding that arises from many etiologies, is defined by a hemoglobin (Hgb) value at least 2 standard deviations below the mean for age and sex (<13 g/dL for men and <12 g/dL for women), although Hgb values may vary due to pregnancy, race, smoking, or altitude. Severe anemia is defined as Hgb <8 g/dL in people of all ages and in both sexes, except in children 6-59 months of age and pregnant women. Anemia results in nonspecific tissue hypoxia symptoms (eg, fatigue, weakness, pallor, dizziness, and fainting). More than one billion individuals are affected by anemia worldwide, and iron deficiency anemia accounts for approximately half of anemia cases. Additional anemias include anemia of chronic disease/anemia of inflammation (anemia related to infections, inflammation, obesity, cancer, and other causes), megaloblastic anemia (caused by vitamin B12 and/or folate deficiency), hemolytic anemias (including sickle cell anemia), and aplastic anemias (related to bone marrow disorders), among others. As anemia treatment depends on the underlying cause, identifying the correct etiology is essential. Initial anemia evaluation includes CBC with platelet count and automated differential, a reticulocyte count and percent, along with a corrected reticulocyte count, and in some cases, review of a peripheral blood smear. Certain circumstances may warrant a bone marrow biopsy.
Last Update: April 2019