How should a patient with iron deficiency anemia, indicated by low MCHC and high RDW on a CBC with differential, be managed and treated?

Management of Iron Deficiency Anemia Based on CBC Findings

Patients with iron deficiency anemia indicated by low MCHC (29.7 g/dL) and high RDW (15.5%) should be treated with oral ferrous sulfate 200 mg three times daily for at least three months after hemoglobin normalization to replenish iron stores. 1

Diagnosis Confirmation

The CBC findings strongly suggest iron deficiency anemia with:

• Low MCHC (29.7 g/dL, below reference range of 31.7-35.3 g/dL)
• Elevated RDW (15.5%, above reference range of 12.2-15.3%)
• Normal hemoglobin (12.9 g/dL)

While the hemoglobin is within normal range, the microcytic indices indicate iron-deficient erythropoiesis. Before initiating treatment, confirm the diagnosis with:

• Serum ferritin (primary test for iron stores)
  • Values <15 μg/dL confirm iron deficiency 1
  • In inflammatory conditions, values <100 μg/dL may still indicate iron deficiency 1
• Transferrin saturation (should be <20% in iron deficiency) 1
• Consider additional tests: serum iron, total iron binding capacity

Treatment Algorithm

First-line Treatment:

• Oral iron supplementation:
  • Ferrous sulfate 200 mg three times daily (provides 65 mg elemental iron per tablet) 1, 2
  • Alternative formulations if not tolerated: ferrous gluconate or ferrous fumarate 1
  • Consider liquid preparations for patients who cannot tolerate tablets 1

Optimization Strategies:

• Take iron on an empty stomach to maximize absorption
• Add vitamin C (ascorbic acid) to enhance iron absorption if response is poor 1
• Consider alternate-day dosing rather than daily dosing to improve absorption and reduce side effects 3
• Monitor response with repeat CBC at 2-4 weeks; expect hemoglobin to rise by 2 g/dL after 3-4 weeks 1

For Poor Response:

• If hemoglobin increase is <1.0 g/dL after 14 days, consider switching to IV iron 4
• Parenteral iron should be used when there is:
  • Intolerance to at least two oral preparations
  • Non-compliance
  • Malabsorption
  • Need for rapid correction 1

Underlying Cause Investigation

All patients with iron deficiency anemia should be evaluated for the underlying cause:

• For patients >45 years:
  • Upper GI endoscopy with small bowel biopsy
  • Colonoscopy or barium enema 1
• For menstruating women <45 years:
  • Assess menstrual blood loss (common cause in this population)
  • Upper GI endoscopy only if upper GI symptoms present 1
• Consider screening for celiac disease with antiendomysial antibodies 1
• Exclude other causes: gastrointestinal bleeding, malabsorption, dietary insufficiency

Follow-up and Monitoring

• Continue iron therapy for three months after hemoglobin normalization to replenish iron stores 1
• Monitor hemoglobin and red cell indices at 3-month intervals for one year, then after another year 1
• Provide additional iron if hemoglobin or MCV falls below normal range 1
• Consider further investigation if hemoglobin cannot be maintained despite adequate iron supplementation 1

Common Pitfalls to Avoid

• Stopping iron supplementation once hemoglobin normalizes (without replenishing stores)
• Failing to investigate underlying cause of iron deficiency
• Overlooking iron deficiency in patients with normal hemoglobin but abnormal red cell indices
• Not addressing adherence issues with oral iron (gastrointestinal side effects are common)
• Misdiagnosing anemia of chronic disease as iron deficiency (check inflammatory markers)

By following this structured approach, iron deficiency anemia can be effectively diagnosed, treated, and monitored to improve patient outcomes and quality of life.