Upon completion of the chapter, the reader will be able to:
Discuss common causes of anemia.
Identify common signs and symptoms of anemia.
Describe diagnostic evaluation required to determine the etiology of anemia.
Develop a treatment regimen considering the underlying cause and patient-specific variables.
Compare and contrast oral and parenteral iron preparations.
Explain the optimal use of folic acid and vitamin B12 in patients with macrocytic anemia.
Evaluate the proper use of epoetin and darbepoetin in patients with anemia caused by cancer chemotherapy or chronic kidney disease.
Develop a plan to monitor the outcomes of pharmacotherapy for the treatment of anemia.
Anemia is a deficiency of erythrocytes with a corresponding reduction in the concentration of hemoglobin (Hgb) that results in reduced oxygen-carrying capacity of the blood. Some patients with anemia may be asymptomatic initially, but eventually, the lack of oxygen to tissues results in fatigue, lethargy, shortness of breath, headache, edema, and tachycardia. Common causes include blood loss, decreased functional red blood cell (RBC) production, and increased RBC destruction. Determination of the underlying cause of anemia is essential for successful management.
EPIDEMIOLOGY AND ETIOLOGY
Anemia is a common diagnosis with a prevalence that varies widely based on age, gender, and race/ethnicity (Table 66–1).1,2 Patients with specific comorbidities such as cancer and chronic kidney disease (CKD) have significantly higher rates of anemia. The incidence of anemia in cancer patients ranges from 30% to 90%. Contributing factors include the underlying malignancy and myelosuppressive antineoplastic therapy.3 The prevalence of anemia in patients with CKD ranges from 15% to 20% in patients with CKD stages 1 through 3 and up to 70% in patients with stage 5.4
Table 66–1Prevalence of Anemia1,2 |Favorite Table|Download (.pdf) Table 66–1 Prevalence of Anemia1,2
|Children (1–5 years) ||43% |
|Males (17–84 years) ||29% |
|Males (85+ years) ||26% |
|Females (15–49 years, pregnant) ||38% |
|Females (15–49 years, nonpregnant) ||29% |
|Females (85+ years) ||20% |
A decrease in erythrocyte production can be multifactorial. Nutritional deficiencies (iron, vitamin B12, and folic acid) are common causes and often easily treatable. Patients with cancer or CKD are at risk for developing anemia caused by dysregulation of iron and erythropoietin (EPO) hemostasis. Patients with chronic immune-related diseases such as rheumatoid arthritis and systemic lupus erythematosus are also at increased risk to develop anemia as a complication of their disease. Anemia related to chronic inflammatory conditions is termed anemia of chronic disease (ACD).5
Drug therapy is the mainstay of treatment for anemias caused by reduced RBC production and is the focus of this chapter. Anemia due to the destruction of erythrocytes, such as with blood loss or hemolytic anemia, will not be discussed.6