CE/CME

Diagnosing and Classifying Anemia in Adult Primary Care

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NORMOCYTIC ANEMIA

In normocytic anemia, the hemoglobin is low but the MCV is normal (see Figure).1 The history and physical exam should provide clues about whether the underlying cause of the anemia requires emergent (eg, active bleeding) or nonemergent (eg, anemia of chronic disease) management. Some of the causes of normocytic anemia are active bleeding, pregnancy, malnutrition, renal failure, chronic disease, hemolytic disorders, hypersplenism, congenital disorders, endocrine disorders, infection, and primary bone marrow disorders.1,5 Expanded plasma volume, as seen in pregnancy and overhydration, can also cause normocytic anemia.5 If gastrointestinal bleeding is suspected or the patient reports dark, tarry stools consistent with melena, fecal occult blood testing should be done. A positive result strongly supports gastrointestinal bleeding as the cause of the anemia.18

The reticulocyte count can also be helpful in identifying the cause of this type of anemia. A normocytic anemia with a normal reticulocyte and normal RDW count is usually related to chronic disease.1,10 For example, chronic kidney disease (CKD) is associated with decreased EPO production due to impaired renal function, which leads to reduced erythropoiesis. Decreased EPO prevents the bone marrow from making red blood cells, resulting in anemia. However, a normocytic anemia with an elevated reticulocyte count points to bleeding or hemolysis, as the reticulosis shows that the bone marrow is increasing red cell production to make up for the lost red cells.5

Additional diagnostic laboratory testing for patients with normocytic anemia may involve, for example, creatinine and blood urea nitrogen for patients with CKD, prothrombin time with an INR and liver function tests for patients with liver disease, and urine human chorionic gonadotropin if pregnancy is suspected.

For patients with an infection that is causing severe hemolysis (eg, sepsis due to a ß-hemolytic streptococcal infection), blood cultures should be drawn.5 If red blood cell destruction due to an artificial cardiac valve or an autoimmune disorder is suspected as the cause of the anemia, a hematology consult is needed.1 Anemia caused by disseminated intravascular coagulation or thrombotic thrombocytopenic purpura resulting in hemolysis are usually emergent conditions that require immediate intervention, including hospitalization and management by a hematologist.1

PATIENT EDUCATION

Patients and any accompanying family members should be educated about the signs and symptoms of anemia, the diagnostic testing and treatment regimens specific to their anemia, and medication compliance issues.

For instance, patients who abuse alcohol often have both vitamin B12 and folate deficiencies. If the macrocytosis is caused by alcohol intake, then the provider should educate the patient on the importance of alcohol abstention, as well as refer the patient for rehabilitation and psychologic counseling, as needed. These patients can sometimes recover from macrocytic anemia simply by stopping alcohol intake and improving their nutrition.19 Patients with microcytosis due to iron deficiency anemia should be advised about the importance of good nutrition and compliance with iron supplementation.

Repeat CBCs and a follow-up patient history and physical exam will help the provider assess whether the anemia is resolving. Individualized plans that target the specific type of anemia identified, as well as its underlying cause, are key to successful treatment.

CONCLUSION

When managing a patient with anemia, providers must define the type of anemia present and identify its underlying cause before starting treatment. Clues from the patient’s history, physical exam, and CBC can help isolate the cause of anemia. The MCV is the most helpful of the red blood cell indices because it allows the provider to classify the anemia as microcytic, macrocytic, or normocytic.

In cases in which the anemia is acute or ­severe—or in which the patient remains anemic even after being treated by the primary care provider—referral to a specialist is ­appropriate.

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