What is the treatment for low iron saturation?

Treatment of Low Iron Saturation

Low iron saturation (<16% in adults) indicating iron deficiency should be treated with oral iron supplementation as first-line therapy, specifically ferrous sulfate 325 mg daily (containing 65 mg elemental iron), taken on an empty stomach when possible, with response assessed at 4 weeks by checking hemoglobin increase of ≥1 g/dL. 1

Diagnostic Confirmation Before Treatment

Before initiating treatment, confirm iron deficiency based on clinical context:

• Without inflammation: Transferrin saturation <16% confirms iron deficiency 1
• With inflammation present: Use ferritin alongside transferrin saturation, as ferritin <100 μg/L with transferrin saturation <16% suggests combined iron deficiency and anemia of chronic disease 1
• Serum ferritin remains the most specific test: <15 μg/L indicates absolute iron deficiency, while <30-45 μg/L suggests depleted stores 1

First-Line Treatment: Oral Iron Supplementation

Dosing by Age Group

Infants and young children: 3 mg/kg per day of elemental iron, administered between meals 1

School-age children (5-12 years): One 60 mg elemental iron tablet daily 1

Adolescent boys (12-18 years): Two 60 mg elemental iron tablets daily 1

Adults: Ferrous sulfate 325 mg daily (65 mg elemental iron) or alternate-day dosing 1, 2, 3

Optimization of Oral Iron Absorption

• Take on empty stomach for maximum absorption, though taking with meals improves tolerance in some patients 1
• Add vitamin C 500 mg to enhance absorption even when calcium or fiber present 1
• Take with meat protein when feasible to improve absorption 1
• Avoid excessive dosing: Preparations with 28-50 mg elemental iron may reduce gastrointestinal side effects and improve compliance 4

Monitoring Response to Oral Iron

At 4 weeks: Recheck hemoglobin/hematocrit 1

• Hemoglobin increase ≥1 g/dL or hematocrit increase ≥3% confirms iron-deficiency anemia diagnosis 1
• If confirmed, continue treatment for 2 additional months, then recheck 1
• Reassess approximately 6 months after successful treatment completion 1

At 8-10 weeks: For non-anemic iron deficiency, repeat basic blood tests to measure treatment success 4

When Oral Iron Fails

If no response after 4 weeks despite compliance and absence of acute illness, further evaluate with:

• Mean cell volume (MCV)
• Red cell distribution width (RDW)
• Serum ferritin concentration 1

Ferritin >15 μg/L suggests iron deficiency is not the cause of anemia 1

Second-Line Treatment: Intravenous Iron

Intravenous iron is indicated when: 1, 3

• Oral iron intolerance (gastrointestinal side effects)
• Impaired absorption (celiac disease, post-bariatric surgery, atrophic gastritis)
• Chronic inflammatory conditions (chronic kidney disease, heart failure, inflammatory bowel disease, cancer)
• Ongoing blood loss
• Second and third trimesters of pregnancy
• Urgent need for rapid iron repletion

Important Caveats for IV Iron

Monitor for potential complications: 5

• Allergic reactions
• Hypophosphatemia/osteomalacia
• Iron overload
• Vascular leakage

Dietary Counseling

Always combine iron supplementation with dietary counseling to address underlying inadequate intake: 1

• Increase dietary sources of heme iron (meat, poultry, fish)
• Include iron absorption enhancers (vitamin C-rich foods)
• Avoid iron absorption inhibitors (calcium, tea, coffee) near iron-rich meals 4

Special Populations

Pregnant women: Require higher iron stores; IV iron preferred in second and third trimesters if oral iron insufficient 1, 3

Patients with inflammatory bowel disease: Endoscopic treatment of bleeding sources should accompany iron replacement 1

Celiac disease patients: Ensure gluten-free diet adherence to improve iron absorption before escalating to IV iron 1

Common Pitfalls to Avoid

• Do not use race-specific cutoffs for anemia screening, as this may lead to missed diagnoses, though be aware that standard cutoffs have lower positive predictive value in Black patients 1
• Do not ignore inflammation: Ferritin is an acute-phase reactant; use transferrin saturation and consider higher ferritin thresholds (up to 100 μg/L) when inflammation present 1
• Do not continue long-term supplementation with normal or high ferritin values, as this is potentially harmful 4
• Do not assume compliance: Gastrointestinal side effects reduce adherence; consider alternate-day dosing or lower elemental iron content formulations 1, 6, 4