What is the initial treatment and frequency of bloodwork for patients with iron deficiency anemia?

Initial Treatment and Monitoring for Iron Deficiency Anemia

The initial treatment for iron deficiency anemia should be oral iron supplementation with ferrous sulfate 200 mg three times daily, and hemoglobin levels should be checked after 3-4 weeks of treatment to assess response. 1, 2

Initial Treatment Approach

First-Line Therapy: Oral Iron Supplementation

• Recommended regimen: Ferrous sulfate 200 mg three times daily (provides ~65 mg elemental iron per tablet) 1, 2
• Alternative oral preparations with similar effectiveness:
  • Ferrous gluconate 300 mg (37 mg elemental iron)
  • Ferrous fumarate 210 mg (69 mg elemental iron) 1
• Consider liquid preparations when tablets are not tolerated 1
• Adding ascorbic acid (vitamin C) enhances iron absorption and should be considered when response is poor 1

Alternative Dosing Strategies

• Once-daily dosing or alternate-day dosing may be as effective with fewer side effects 1, 2
• 60 mg elemental iron twice daily produces faster hemoglobin rise than 120 mg on alternate days, though similar results are achieved after the same total dose 1

Parenteral Iron Indications

Parenteral iron should be reserved for patients with:

• Intolerance to at least two oral preparations
• Non-compliance
• Malabsorption
• Continued blood loss 1, 2

Monitoring Response to Treatment

Initial Follow-up

• Check hemoglobin concentration after 3-4 weeks of treatment 1, 2
• Expected response: Hemoglobin rise of approximately 2 g/dL after 3-4 weeks 1
• A hemoglobin increase of at least 1.0 g/dL at day 14 strongly predicts adequate subsequent response (sensitivity 90.1%, specificity 79.3%) 1, 3

Inadequate Response

If hemoglobin fails to rise by at least 1 g/dL after 2-4 weeks, consider:

• Poor compliance
• Misdiagnosis
• Continued blood loss
• Malabsorption
• Concurrent deficiency of vitamin B12 or folic acid 1

Long-term Monitoring

• Continue iron supplementation for 3-6 months after hemoglobin normalization to replenish iron stores 2
• Target hemoglobin levels: >12 g/dL for women and >13 g/dL for men 2
• Target ferritin level: >100 ng/mL 2
• Target transferrin saturation: >20% 2

Special Considerations

Diagnostic Workup

• Serum ferritin <30 ng/mL or transferrin saturation <20% confirms iron deficiency 2, 4
• For patients >45 years old with iron deficiency anemia, both upper and lower GI investigations are recommended to rule out malignancy 1
• For patients <45 years, only those with upper GI symptoms should have endoscopy and small bowel biopsy 1
• Consider testing for celiac disease with anti-endomysial antibodies and IgA measurement 1, 2

Pregnancy Considerations

• Treat anemia in pregnancy with 60-120 mg/day of elemental iron 1
• If hemoglobin concentration is <9.0 g/dL or hematocrit <27.0%, refer to a physician familiar with anemia during pregnancy 1
• When hemoglobin normalizes for gestational stage, decrease iron dose to 30 mg/day 1

Common Pitfalls to Avoid

1. Inadequate follow-up: Failure to check hemoglobin after 3-4 weeks may miss non-responders
2. Premature discontinuation: Stopping iron too early before stores are replenished
3. Overlooking underlying cause: Not investigating the source of iron deficiency, especially in men and postmenopausal women
4. Inappropriate parenteral iron use: Using IV iron as first-line therapy when oral iron would be effective
5. Missing concomitant conditions: Not considering other causes of anemia such as thalassemia minor or sickle cell trait in patients with appropriate ethnic backgrounds 1

By following this structured approach to treatment and monitoring, most patients with iron deficiency anemia will achieve resolution of anemia and replenishment of iron stores, leading to improved quality of life and reduced symptoms.