In an adult with iron‑deficiency anemia, how many times can IV iron‑dextran be given, what is the minimum interval between doses, and what is the maximum weekly amount?

How Many Times Can IV Iron Dextran Be Given?

IV iron dextran can be given repeatedly as needed based on iron parameters, with no absolute limit on the number of courses—the key is monitoring transferrin saturation (TSAT) and ferritin levels to guide dosing frequency and prevent iron overload.

Dosing Frequency and Intervals

Initial Treatment Course

• Standard regimen: Administer 100-125 mg IV weekly for 8-10 consecutive weeks (total 1,000 mg) when TSAT is <20% and/or ferritin is <100 ng/mL 1
• Alternative single-dose option: For non-hemodialysis patients (home hemodialysis, peritoneal dialysis, or CKD patients), 500-1,000 mg can be given as a single infusion after a 25 mg test dose 1
• Minimum interval between large doses: Wait at least 2 weeks after doses ≥1,000 mg before reassessing iron parameters 1

Repeat Courses

• If inadequate response: A second course of 1,000 mg IV over 8-10 weeks can be administered if the first course does not increase hemoglobin/hematocrit or iron parameters 1
• For ongoing maintenance: Once target levels are achieved (TSAT ≥20%, ferritin ≥100 ng/mL), continue 25-125 mg weekly indefinitely as needed to maintain targets 1
• Unlimited repetition: Iron dextran courses can be repeated as many times as necessary, provided iron parameters remain below safety thresholds 1

Maximum Weekly and Total Amounts

Weekly Dosing Limits

• Hemodialysis patients: 100-125 mg per dose, up to 3 times weekly, for a maximum of approximately 300-375 mg/week during induction phases 1
• Non-hemodialysis patients: Can receive up to 1,000 mg in a single weekly infusion 1

Total Cumulative Dose Per Course

• Standard course: 1,000 mg total over 8-10 weeks (100-125 mg weekly × 8-10 doses) 1
• Maximum per 12-week period: Guidelines suggest 250-1,000 mg can be administered within any 12-week period using various schedules 1

Mandatory Safety Thresholds for Withholding

When to STOP Iron Administration

• Withhold iron when:
  • TSAT exceeds 50% AND/OR
  • Ferritin exceeds 800 ng/mL 1, 2
• Duration of withholding: Stop for up to 3 months, then remeasure iron parameters before resuming 1
• Resumption protocol: When levels fall below these thresholds, restart at a dose reduced by one-third to one-half of the previous maintenance dose 1

Monitoring Requirements

Frequency of Laboratory Assessment

• During active treatment: Check TSAT and ferritin at least every 3 months in patients receiving IV iron 1
• After dose adjustment: Monitor every 3-6 months once stable maintenance is achieved 1

Timing Restrictions for Accurate Measurement

• Small doses (100-125 mg/week): Can measure iron parameters without interrupting therapy 1
• Medium doses (200-500 mg): Wait at least 7 days before measuring 1
• Large doses (≥1,000 mg): Wait at least 2 weeks before accurate assessment 1

Practical Dosing Algorithms

For Hemodialysis Patients

1. Initial phase: 100-125 mg weekly × 8-10 weeks 1
2. Reassess: Measure TSAT and ferritin
3. If still deficient: Repeat another 8-10 week course 1
4. Maintenance: 25-125 mg weekly indefinitely to maintain TSAT ≥20% and ferritin ≥100 ng/mL 1

For Non-Hemodialysis Patients

1. Single-dose option: 500-1,000 mg as one infusion (after 25 mg test dose) 1
2. Reassess at 2 weeks: Check for adverse reactions and initial response
3. Reassess at 3-4 months: Measure iron parameters 3
4. Repeat as needed: Additional single doses can be given when deficiency recurs 3

Critical Safety Considerations

Test Dose Requirement

• Mandatory 25 mg test dose before the first therapeutic dose of iron dextran 4
• This distinguishes iron dextran from newer formulations (ferric gluconate, iron sucrose) which do not require test doses 5

Adverse Reaction Risk

• Anaphylactoid reactions: Occur in approximately 0.6-0.7% of patients, with 3 life-threatening reactions reported per 2,099 injections in one series 6
• No fatalities have been documented with modern protocols using premedication 7
• Delayed reactions: More common in women and patients with collagen-vascular diseases 6

Administration Setting Requirements

• Must be given in a facility with personnel and equipment immediately available to treat anaphylaxis 2
• Mandatory observation: At least 30 minutes post-infusion 4, 2

Common Pitfalls to Avoid

• Do not exceed 100-125 mg per dose in hemodialysis patients to minimize arthralgias and myalgias 1, 2
• Do not measure iron studies too soon after large doses—spuriously elevated values will lead to inappropriate withholding of therapy 1
• Do not continue iron when TSAT >50% or ferritin >800 ng/mL—this risks iatrogenic hemosiderosis 1, 2
• Do not confuse iron dextran with ferric gluconate or iron sucrose—they have different dosing limits and safety profiles 1, 5
• Do not skip the test dose for iron dextran, even though it is not required for newer formulations 4

Cost and Practical Considerations

• Iron dextran allows flexible dosing: Can be given as small frequent doses (100-125 mg weekly) or large single doses (500-1,000 mg) depending on clinical setting 1, 7, 8
• Cost-effectiveness: Higher-dose, less-frequent regimens (500 mg × 2 weeks) are 35% more cost-effective than lower-dose, more-frequent regimens (200 mg × 5 weeks) with equivalent efficacy 8
• Newer formulations: While ferric carboxymaltose and ferric derisomaltose allow 1-2 infusion protocols, they cost significantly more ($3,470-$3,896 vs $610-$1,490 for iron dextran) 5