anemia /ənē″mē·ə/ [Gk, a + haima, without blood] , inadequate tissue oxygenation. Usually caused by inadequate blood oxygen-carrying capacity. Anemia may be secondary to a decreased erythrocyte count, a decrease in quality hemoglobin to below the reference interval of 12 to 16 g/dL for women and 13.5 to 18 g/dL for men. Anemia may be caused by a decrease in erythrocyte production, an increase in erythrocyte destruction, or a loss of blood. A morphological classification system describes anemia by the hemoglobin content of the erythrocytes (normochromic or hypochromic) and by differences in erythrocyte size (macrocytic, normocytic, or microcytic). Any one of three tests (hemoglobin, hematocrit, or red blood cell count) can be used to diagnose anemia. See also hemolytic anemia, hypoplastic anemia, iron deficiency anemia, iron metabolism. ▪ OBSERVATIONS: Signs and symptoms include fatigue, exertional dyspnea, dizziness, headache, insomnia, pallor, confusion, or disorientation. Anorexia, dyspepsia, palpitations, tachycardia, cardiac dilation, and systolic murmurs also may occur. Iron deficiency is the most common cause. Additional laboratory studies may be required to establish the less common forms of anemia. ▪ INTERVENTIONS: The therapeutic response to anemia is variable and depends on the causative factors. Moderate to severe anemia, with hemoglobin levels that are below 7 to 8 g/dL, may require transfusion of one or more units of packed red blood cells, especially if the condition is acute and specific clinical signs are present. Depending on the kind of anemia, treatment includes providing supplements of the deficient component, eliminating the cause of the blood loss, or alleviating the hemolytic component. The latter may involve administration of adrenal corticosteroids or splenectomy. Appropriate laboratory tests are repeated at intervals to monitor the response and need for continued therapy. Erythropoietin injections may be used to stimulate erythrocyte production when anemia is secondary to chronic renal failure, the anemia of chronic disease, or chemotherapy.
