What is the recommended dose of iron dextran (intravenous iron) for an adult patient with iron deficiency without anemia who has gastrointestinal issues and cannot tolerate oral iron?

Dosing Iron Dextran for Iron Deficiency Without Anemia

For a patient with iron deficiency without anemia who cannot tolerate oral iron, administer 500-1000 mg of intravenous iron dextran as the total replacement dose, given the absence of anemia means lower iron deficit compared to anemic patients. 1

Rationale for IV Iron in This Clinical Scenario

Your patient meets clear criteria for intravenous iron therapy based on the 2024 AGA guidelines, which state that IV iron should be used when patients do not tolerate oral iron. 1 This is appropriate first-line therapy in this context, not a second-line option. 1

Calculating the Appropriate Dose

For Iron Deficiency WITHOUT Anemia:

• Minimum dose: 500-1000 mg total 1
• The European consensus guidelines specifically note that estimation of iron needs in iron deficiency without anemia is not covered by standard formulas like Ganzoni's, but recommend a minimum of 500-1000 mg should be considered 1
• This is substantially less than the 1500-2000 mg typically needed for patients with iron deficiency anemia 1

Why Standard Formulas Don't Apply:

The Ganzoni formula [body weight in kg × (target Hb - actual Hb in g/dL) × 0.24 + 500] is designed for anemic patients and underestimates requirements even in that population. 1 Since your patient has normal hemoglobin, this formula cannot be used. The 500 mg component of the formula represents storage iron replacement, which is your primary target here. 1

Practical Administration of Iron Dextran

Critical Safety Considerations:

• Mandatory test dose required: Low molecular weight iron dextran (INFeD) carries a boxed warning for anaphylaxis risk and requires a test dose before full administration 1
• Consider premedication with diphenhydramine, cimetidine, and dexamethasone to reduce infusion reactions 2
• Must have resuscitation capabilities available during administration 1

Dosing Schedule:

• Iron dextran can be given as a total dose infusion of >1000 mg in a single session, which is its main advantage over other IV iron formulations 1
• For your patient with iron deficiency without anemia, a single infusion of 500-1000 mg would be appropriate 1
• Alternative approach: 500 mg doses can be given safely if you prefer divided dosing 2

Alternative IV Iron Formulations to Consider

The 2024 AGA guidelines recommend IV iron formulations that can replace iron deficits with 1 or 2 infusions over those requiring more than 2 infusions. 1 Given this preference and safety considerations:

Potentially Better Options Than Iron Dextran:

• Ferric carboxymaltose: 500-1000 mg single doses (up to 20 mg/kg), no test dose required, 15-minute infusion 1
• Ferumoxytol: 510 mg × 2 doses, no test dose required 1
• Iron isomaltoside: 1000 mg single dose (available in Europe), no test dose required 1

These formulations have similar safety profiles to iron dextran but don't require test dosing, making them more convenient. 1 True anaphylaxis is very rare with all IV iron formulations; most reactions are complement activation-related pseudo-allergy (infusion reactions). 1

Iron Dextran Remains Appropriate If:

• Cost is a primary concern (iron dextran is the least expensive IV formulation) 1
• You need the flexibility of total dose infusion >1000 mg 1
• Other formulations are not available at your institution

Monitoring Response

• Recheck ferritin and transferrin saturation in 4-8 weeks 1
• Target ferritin >100 μg/L to prevent rapid recurrence 1
• Consider re-treatment when ferritin drops below 100 μg/L 1

Common Pitfall to Avoid

Do not underdose simply because the patient is not anemic. Iron deficiency without anemia still requires adequate storage iron replacement (500-1000 mg), not just a token amount of IV iron. 1 Inadequate dosing will lead to rapid recurrence of deficiency.