What is the next step in managing a patient with anemia, as indicated by low red blood cell count, hemoglobin, and hematocrit, with an elevated Red Cell Distribution Width (RDW)?

Management of Anemia with Elevated RDW

The next step in managing this patient with normocytic anemia (normal MCV 94.2) and elevated RDW (16.1%) should be a comprehensive iron studies panel including serum ferritin, transferrin saturation, reticulocyte count, and evaluation for underlying causes. 1, 2

Initial Assessment of Anemia

• The CBC shows anemia with low hemoglobin (9.5 g/dL), low hematocrit (30.7%), and low RBC count (3.26 million/uL), indicating significant anemia requiring further evaluation 1
• The normal MCV (94.2 fL) with elevated RDW (16.1%) suggests a normocytic anemia with increased red cell size variation, which can indicate early iron deficiency, mixed nutritional deficiencies, or other causes 1, 2
• The low MCHC (30.9 g/dL) suggests hypochromia, which often accompanies iron deficiency even when MCV remains normal 1

Recommended Diagnostic Workup

• Obtain iron studies including serum ferritin, transferrin saturation, and total iron-binding capacity to assess iron status 1, 2
• Measure reticulocyte count to evaluate bone marrow response to anemia - a low count suggests inadequate production while a high count suggests hemolysis or blood loss 1, 2
• Check vitamin B12 and folate levels, as deficiencies can coexist with iron deficiency and contribute to elevated RDW 2
• Consider inflammatory markers (C-reactive protein, erythrocyte sedimentation rate) to evaluate for anemia of chronic disease 2

Interpretation of RDW in Context

• Elevated RDW (>15.0%) with normal MCV can be an early indicator of iron deficiency before microcytosis develops 1, 3
• RDW elevation has been shown to correlate with severity of iron deficiency, with higher values associated with lower transferrin saturation 3
• While RDW is elevated in 90% of iron deficiency cases, it can also be elevated in other conditions including vitamin B12/folate deficiency, hemoglobinopathies, and myelodysplastic syndromes 4, 2

Clinical Considerations

• Assess for potential sources of blood loss (gastrointestinal, menstrual) as iron deficiency in adults often indicates ongoing blood loss 1, 2
• In patients without obvious blood loss, gastrointestinal evaluation may be warranted as occult GI bleeding is a common cause of iron deficiency anemia in adults 1
• If iron deficiency is confirmed, initiate iron supplementation while continuing to investigate underlying cause 2
• For severe symptomatic anemia (Hb <8 g/dL with symptoms), consider blood transfusion, particularly if the patient is experiencing fatigue, dizziness, or hypotension 1

Pitfalls to Avoid

• Do not assume iron deficiency based solely on RDW without confirmatory iron studies, as multiple conditions can cause elevated RDW 4, 5
• Avoid attributing anemia to a single cause without complete evaluation, as multiple nutritional deficiencies can coexist 2
• Remember that normal MCV does not rule out iron deficiency, especially in early stages or when mixed deficiencies are present 6
• Do not delay investigation of underlying causes while treating the anemia, particularly in adults where malignancy may be a concern 2