What is the best course of treatment for a patient with low ferritin and iron saturation levels, indicating iron deficiency anemia?

Treatment of Low Ferritin and Iron Saturation (Iron Deficiency)

All patients with low ferritin and iron saturation should receive iron supplementation to correct anemia and replenish body stores, with oral iron as first-line therapy in most cases, but intravenous iron preferred for patients with active inflammation, severe anemia (Hb <10 g/dL), or oral iron intolerance. 1, 2

Diagnostic Confirmation

Before initiating treatment, confirm iron deficiency with appropriate thresholds:

• Without inflammation: Ferritin <30 ng/mL or ferritin 30-100 ng/mL with transferrin saturation <20% 1, 2, 3
• With inflammation present: Ferritin <100 ng/mL indicates iron deficiency (ferritin is an acute phase reactant and falsely elevated) 1
• Transferrin saturation <20% supports diagnosis in all contexts 1, 3

Treatment Algorithm

First-Line: Oral Iron Therapy

Oral iron is appropriate for patients with:

• Clinically inactive disease 1
• Mild anemia (Hb >10 g/dL) 1
• No previous oral iron intolerance 1
• Adequate gastrointestinal absorption 2

Dosing regimen:

• Ferrous sulfate 200 mg three times daily (or 325 mg daily/alternate days) 1, 2
• Ferrous gluconate or ferrous fumarate are equally effective alternatives 1
• Alternate-day dosing improves absorption and reduces side effects 2, 3
• Ascorbic acid 250-500 mg twice daily enhances absorption 1

Duration: Continue for 3 months after correction of anemia to replenish iron stores 1

Intravenous Iron Indications

IV iron should be considered as first-line treatment in: 1, 2

• Clinically active inflammatory bowel disease 1
• Hemoglobin <10 g/dL (100 g/L) 1
• Previous intolerance to oral iron 1
• Malabsorption conditions (celiac disease, post-bariatric surgery) 2, 3
• Chronic kidney disease 1, 2
• Heart failure 1, 2
• Cancer patients on chemotherapy 1
• Second/third trimester pregnancy 2
• Ongoing blood loss 2

IV iron preparations and dosing:

• Iron sucrose (Venofer): 200 mg over 10 minutes 1
• Ferric carboxymaltose (Ferinject): up to 1000 mg over 15 minutes 1
• Iron dextran (Cosmofer): up to 20 mg/kg over 6 hours (requires 25 mg test dose due to anaphylaxis risk) 1

Total dose: 1000 mg iron for functional deficiency; adjust based on body weight and hemoglobin for absolute deficiency 1

Monitoring Response

Assess treatment response at 2-4 weeks: 2, 3

• Hemoglobin should rise by 2 g/dL after 3-4 weeks 1
• If no response, consider: poor compliance, continued blood loss, malabsorption, misdiagnosis, or inflammatory block 1

For non-responders to oral iron: Switch to intravenous iron 1, 2, 3

Long-term monitoring after correction: 1

• Check hemoglobin and red cell indices every 3 months for 1 year
• Then annually thereafter
• Repeat ferritin if doubt exists about recurrence

Critical Pitfalls to Avoid

Do not give iron supplementation when: 1, 4

• Ferritin >800 ng/mL or transferrin saturation ≥50% (risk of iron overload) 1
• Normal or high ferritin without confirmed deficiency 1, 4

Recognize functional vs. absolute iron deficiency: 1

• Functional deficiency: Ferritin 100-800 ng/mL with transferrin saturation <20% (iron stores present but inadequate mobilization)
• Absolute deficiency: Ferritin <100 ng/mL with transferrin saturation <20% (depleted stores)

Anaphylaxis precautions with IV iron: 1

• Resuscitation facilities must be available
• Test dose required for iron dextran (highest risk: 0.6-0.7% serious reactions) 1
• Newer formulations (ferric carboxymaltose, iron sucrose) have lower risk (<1:250,000) 1

Maintenance Therapy

For recurrent iron deficiency: 1

• Reinitiate IV iron when ferritin drops below 100 μg/L or hemoglobin falls below 12-13 g/dL (gender-dependent) 1
• Proactive maintenance prevents anemia recurrence better than "watch and wait" 1
• Address underlying cause (menorrhagia, GI bleeding, inflammatory disease activity) 1