Chapter 9: Hematology, Oncology, Allergy, and Immunology

RBC DISORDERS

Anemia

Various standards. However, the World Health Organization (WHO) definition: Hemoglobin < 12 g/dL (hematocrit [Hct] < 36%) in women and < 13 g/dL in men (Hct < 39%).

CAUSES

Generally caused by decreased production or increased destruction/loss of new erythrocytes. In the emergent setting, the most common cause of acute anemia is rapid erythrocyte loss from bleeding. Chronic anemia is frequently caused by abnormal erythrocyte formation and can be further categorized by MCV values (Table 9.1).

SYMPTOMS/EXAMINATION FINDINGS

Signs and symptoms are variable and depend on chronicity and severity of anemia. Clinically severe anemia is indicated by hypotension, tachycardia, tachypnea, altered mental status (AMS), chest pain, syncope, AMS, and severe dyspnea.

Patients with chronic anemia generally present with a more insidious onset of dyspnea, decreased exercise tolerance, fatigue, generalized weakness, and orthostatic dizziness. They tend to have more normal vital signs and less pronounced examination abnormalities.

DIAGNOSIS

• Initial laboratory tests include complete blood count (CBC) with differential, reticulocyte count, and peripheral smear.

• Other testing based on clinical suspicion for underlying cause (eg, iron studies, B₁₂ and folate levels, Coombs testing, serum protein electrophoresis [SPEP], etc).

TREATMENT

• Transfuse packed red blood cell (PRBC) as indicated.

  • Symptomatic patients with hemoglobin < 10 g/dL, including patients with acute coronary syndromes.

  • Recent clinical trial evidence proposes a more restrictive policy of transfusing a hemodynamically stable patient to a hemoglobin > 7 g/dL.

  • However, transfuse emergently for any hemodynamically unstable patient.

• Treat underlying causes.

Microcytic Anemia

Defined by an MCV < 80 fL. Causes of microcytic anemia can be remembered by the mnemonic FALTS.

Iron Deficiency

One of the most common causes of microcytic anemia. It may be related to poor intake but should prompt ...