What is the diagnosis and management plan for a patient with mild anemia, as indicated by low hemoglobin and hematocrit levels, and an elevated RDW?

Assessment of Mild Anemia with Elevated RDW

The laboratory values indicate mild anemia with relative lymphocytosis and an elevated red cell distribution width (RDW), most likely representing iron deficiency anemia that requires oral iron supplementation as first-line treatment.

Laboratory Interpretation

• Hemoglobin: 13.6 g/dL (mildly decreased)
• Hematocrit: 41% (mildly decreased)
• RBC: 4.7 million/μL (low normal)
• RDW: 15.3% (elevated, normal range typically 11.5-14.5%)
• Neutrophils: 38% (relative neutropenia)
• Lymphocytes: 55% (relative lymphocytosis)
• Monocytes: 7% (normal)

Diagnosis

The combination of mildly decreased hemoglobin and hematocrit with an elevated RDW strongly suggests iron deficiency anemia (IDA). According to guidelines, mild anemia is defined as hemoglobin between 10-11.9 g/dL 1. The elevated RDW indicates increased variability in red blood cell size (anisocytosis), which is a hallmark of early iron deficiency before significant microcytosis develops 2.

The relative lymphocytosis with neutropenia suggests a possible viral infection or other inflammatory process that may be contributing to the anemia.

Recommended Management

1. Iron Studies

   • Measure serum ferritin, transferrin saturation, and total iron binding capacity to confirm iron deficiency 1
   • Consider measuring reticulocyte count to assess bone marrow response

2. Oral Iron Supplementation

   • First-line treatment: Ferrous sulfate 324 mg daily (providing 65 mg elemental iron) 1
   • Consider alternate-day dosing to improve tolerance and absorption
   • Continue treatment for 3-6 months to replenish iron stores

3. Additional Testing Based on Clinical Context

   • If patient is female of reproductive age, evaluate for menorrhagia
   • If patient is older or male, consider gastrointestinal evaluation for occult blood loss
   • Check vitamin B12 and folate levels to rule out concurrent deficiencies

4. Follow-up

   • Repeat CBC in 4-8 weeks to assess response to iron therapy
   • Target hemoglobin increase of approximately 1 g/dL per month with successful treatment

Special Considerations

• The elevated RDW is often the earliest laboratory finding in iron deficiency, preceding changes in MCV 2
• Relative lymphocytosis may indicate a viral process that could be contributing to anemia
• If no response to oral iron after 4-8 weeks, consider:
  • Poor adherence
  • Malabsorption
  • Ongoing blood loss
  • Alternative diagnosis

Common Pitfalls to Avoid

1. Failing to investigate underlying causes of iron deficiency, especially in males and postmenopausal females
2. Overlooking the significance of elevated RDW as an early marker of iron deficiency
3. Initiating treatment without confirming iron deficiency through appropriate laboratory testing
4. Using inadequate doses of oral iron supplementation
5. Insufficient duration of treatment, leading to recurrence of anemia

The mild nature of this anemia suggests early iron deficiency that should respond well to oral iron supplementation, but identifying and addressing the underlying cause is essential for long-term management.