- Anemia is a group of diseases characterized by a decrease in either hemoglobin (Hb) or the volume of red blood cells (RBCs), which results in decreased oxygen-carrying capacity of the blood. Anemia is defined by the World Health Organization as Hb <13 g/dL (<130 g/L; <8.07 mmol/L) in men and <12 g/dL (<120 g/L; <7.45 mmol/L) in women.
- Acute-onset anemias are most likely to present with tachycardia, lightheadedness, and dyspnea. Chronic anemia often presents with weakness, fatigue, headache, vertigo, and pallor.
- Iron-deficiency anemia (IDA) is characterized by decreased levels of ferritin (most sensitive marker) and serum iron, as well as decreased transferrin saturation. Hb and hematocrit decrease later. RBC morphology includes hypochromia and microcytosis. Most patients are adequately treated with oral iron therapy, although parenteral iron therapy is necessary in selected patient populations.
- Vitamin B12 deficiency, a macrocytic anemia, can be due to inadequate intake, malabsorption syndromes, and inadequate utilization. Anemia caused by lack of intrinsic factor, resulting in decreased vitamin B12 absorption, is called pernicious anemia. Neurologic symptoms can be present and can become irreversible if the vitamin B12 deficiency is not treated promptly. Oral or parenteral therapy can be used for replacement.
- Folic acid deficiency, a macrocytic anemia, results from inadequate intake, decreased absorption, and increased folate requirements. Treatment consists of oral administration of folic acid, even for patients with absorption problems. Adequate folic acid intake is essential in women of childbearing age to decrease the risk of neural tube defects in their children.
- Anemia of inflammation (AI) is a newer term used to describe both anemia of chronic disease and anemia of critical illness. AI is a diagnosis of exclusion. It results from chronic inflammation, infection, or malignancy and can occur as early as 1 to 2 months after the onset of the disease. The serum iron level usually is decreased, but in contrast to IDA, the serum ferritin concentration is normal or increased. Treatment is aimed at correcting the underlying pathology. Anemia of critical illness occurs within days of acute illness.
- Anemia is one of the most prevalent clinical problems in the elderly, although not an inevitable complication of aging. Low Hb concentrations are not “normal” among elders. Anemia is associated with an increased risk of hospitalization and mortality, reduced quality of life, and decreased physical functioning in the elderly.
- IDA is a leading cause of infant morbidity and mortality. Age- and sex-adjusted norms must be used in the interpretation of laboratory results for pediatric patients. Primary prevention of IDA is the goal. A therapeutic trial of oral iron is the standard of care.
On completion of this chapter, the reader will be able to:
Classify an anemia using the following data: reticulocyte count, peripheral blood smear, hemoglobin, hematocrit, red blood cell (RBC) indices, serum iron, total iron-binding capacity, ferritin, folate, vitamin B12, homocysteine, and methylmalonic acid.
Discuss the life cycle of RBCs (development, maturation process, and normal destruction).
Compare and contrast the presenting signs and symptoms of anemia in a patient who develops anemia ...