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LEARNING OBJECTIVES

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  1. Interpret the findings for anemia and its causes, the presence or absence of bacterial infections, and evidence of adverse hematological effects of medication given the results of a complete blood count.

  2. Evaluate for evidence of bleeding due to overanticoagulation when monitoring patients on anticoagulants.

  3. Use knowledge of the complete blood count and other signs and symptoms to monitor the response to treatment for anemias and infections.

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INTRODUCTION

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The purpose of this chapter is to teach pharmacists how to evaluate patients for anemia, bacterial infection, bleeding, and adverse hematological drug effects. Management of anticoagulant therapy, including adjustment of doses, as well as medications that cause various hematological disorders, can be readily found in pharmacotherapy textbooks and other resources. Therefore, these topics are not covered in this chapter. Pharmacists in a variety of patient care practice environments are routinely required to evaluate patients’ complete blood counts to evaluate for potential adverse medication effects and response to treatment. Pharmacists working in anticoagulation clinics routinely monitor for evidence of bleeding due to overanticoagulation. Pharmacists also monitor responses of treatments for various anemias and infections. Finally, pharmacists are also asked to evaluate for the presence of drug-induced adverse effects to the hematologic system.

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INTERPRETING THE COMPLETE BLOOD COUNT

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This review is not intended to be a comprehensive listing of all possible abnormalities, but focuses on the common hematological abnormalities that are typically seen by pharmacists in dealing with adult patients. The complete blood count (CBC) consists of three major components: red cells (RBC), white cells (WBC), and platelets. When evaluating the results of a CBC, consideration should be given to gender, ethnicity, and normal variation. Up to 5% of the population, without any disease, will routinely have values that are outside the “normal” values. In addition, different references cite small differences in normal values. Therefore, this review will use a common sense approach to CBC interpretation and easy to remember normal and abnormal values.

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Red Cells

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When looking at the red cell portion of the CBC, the first thing is to determine whether or not the patient is anemic. Anemia is defined as a decreased red cell mass, manifested as below normal levels of hematocrit (HCT) and red cell count (RBC). Hematocrit is the percentage of blood volume that comprises red blood cells. Values differ in adults by gender due to a combination of the erythropoietic effect of higher levels of testosterone in males, and regular blood loss due to menses in females. Normal values are 42% to 50% in males and 36% to 45% in females. Hemoglobin (HGB) is the oxygen carrying moiety within erythrocytes (RBC). Anemias are characterized by amounts of hemoglobin <13.5 g/dL in males or 12.0 g/dL in females. The red cell count (RBC) is done by instrument and normal values range from 4.5 to 5.9 × 106 in males and 4.1 to 5.1 × 106 in females. The ...

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