DiPiro’s Pharmacotherapy: A Pathophysiologic Approach, 12th Edition

Chapter 122: Anemias

Kristen M. Cook; Devon M. Greer

CHAPTER SUMMARY FROM THE PHARMACOTHERAPY HANDBOOK

For the Chapter in the Schwinghammer Handbook, please go to Chapter 33, Anemias.

KEY CONCEPTS

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 (WHO) as Hb less than 13 g/dL (130 g/L; 8.07 mmol/L) in men and less than 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 ferritin levels (most sensitive marker) and serum iron, and 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 some patients.
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 is usually 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 a common problem in older adults, although not an inevitable complication of aging. Low Hb concentrations are not “normal” in older adults. Anemia is associated with an increased risk of hospitalization and mortality, reduced quality of life, and decreased physical functioning in older adults.
IDA is a leading cause of infant morbidity and mortality worldwide. Age- and sex-adjusted norms must be used to interpret laboratory results for pediatric patients. Primary prevention of IDA is the goal because physical and mental developmental delays can be irreversible.