What iron dosage should be given to a 60-year-old man with low ferritin, normal serum iron, and normal total iron‑binding capacity?

Iron Supplementation for Non-Anemic Iron Deficiency

For a 60-year-old man with ferritin of 30 μg/L but normal serum iron and TIBC, oral iron supplementation with 50-100 mg elemental iron on alternate days is the recommended approach, as this represents non-anemic iron deficiency that warrants treatment. 1, 2

Diagnosis Confirmation

This patient has non-anemic iron deficiency (NAID), defined as depleted iron stores (ferritin <30 μg/L) without anemia:

• Ferritin <30 μg/L indicates low body iron stores, even though the lower limit of normal for most laboratories ranges from 15-30 μg/L 3
• A ferritin cutoff of 30 μg/L is appropriate for healthy adults over 15 years 2
• Normal serum iron and TIBC do not exclude iron deficiency when ferritin is low 3

Important caveat: Ensure there is no underlying inflammation (check C-reactive protein), as ferritin is an acute phase protein and can be falsely normal or elevated despite iron deficiency 2. However, in this case with normal iron and TIBC, inflammation is less likely.

Treatment Approach

Oral Iron Dosing Strategy

Optimal regimen: 50-100 mg elemental iron given as a single morning dose on alternate days 4:

• Doses ≥60 mg stimulate acute hepcidin elevation that persists 24 hours, reducing absorption of subsequent doses 4
• Alternate-day dosing maximizes fractional iron absorption compared to daily dosing 4
• Morning administration is preferred over afternoon/evening dosing due to circadian hepcidin patterns 4

Specific formulation options:

• Ferrous sulfate 325 mg daily (65 mg elemental iron) or on alternate days 1
• Lower doses (28-50 mg elemental iron) reduce gastrointestinal side effects while maintaining efficacy 2
• In elderly patients specifically, even 15 mg daily has proven effective, though 50 mg provides faster repletion 5

Why Not Higher Doses?

Traditional recommendations of 150-200 mg elemental iron daily are not optimal 4:

• Fractional absorption decreases with higher doses 4
• Unabsorbed iron causes gut irritation, inflammation, and dysbiosis 4
• Side effects (abdominal discomfort, nausea, constipation, black stools) increase significantly with doses >50 mg 5
• Elderly patients are particularly vulnerable to dose-dependent adverse effects 5

Monitoring and Follow-up

Laboratory reassessment at 8-10 weeks 2:

• Repeat CBC and iron parameters (ferritin, transferrin saturation) 6, 2
• Target ferritin: ≥50 ng/mL in the absence of inflammation 6
• Hemoglobin should increase by 1-2 g/dL within 4-8 weeks if anemia develops or was subclinical 6

Long-term management:

• If ferritin remains low after 8-10 weeks, continue intermittent oral supplementation 2
• Monitor iron stores every 6-12 months in patients with recurrent deficiency 2
• Investigate underlying causes: gastrointestinal blood loss, malabsorption (celiac disease, atrophic gastritis), dietary insufficiency, or NSAID use 1

When to Consider Intravenous Iron

IV iron is not indicated for this patient unless 6, 1:

• Oral iron intolerance develops
• Malabsorption is documented (celiac disease, post-bariatric surgery, autoimmune gastritis)
• Chronic inflammatory conditions are present (CKD, heart failure, IBD, cancer)
• Ongoing blood loss cannot be controlled

Critical Pitfalls to Avoid

• Do not ignore non-anemic iron deficiency: Even without anemia, iron deficiency causes fatigue, cognitive impairment, exercise intolerance, and restless legs syndrome 1, 2
• Do not use daily divided doses: This reduces absorption and increases side effects 4
• Do not supplement if ferritin normalizes: Long-term supplementation with normal/high ferritin is potentially harmful 2
• Do not check iron parameters within 4 weeks of starting treatment: Circulating iron interferes with assays, producing spurious results 6