What is the recommended number of doses of intravenous (IV) iron for a patient with iron deficiency anemia and low ferritin levels?

IV Iron Dosing for Iron Deficiency with Low Anemia

For patients with low ferritin and mild anemia, administer a total cumulative dose of 1,000 mg of IV iron, divided into multiple doses given over several weeks, with the specific regimen depending on the clinical setting and iron formulation used.

Dosing Regimens by Clinical Context

Hemodialysis Patients

• Standard regimen: 100 mg IV iron per hemodialysis session for 10 consecutive sessions (total 1,000 mg) 1
• Administer early during dialysis, typically within the first hour 2
• Alternative: 25-100 mg weekly for 10 weeks 1
• Maintenance dosing: 250-1,000 mg total within 12 weeks, given thrice weekly, twice weekly, weekly, or every other week 1

Non-Dialysis Chronic Kidney Disease (NDD-CKD)

• Primary regimen: 200 mg IV iron on 5 different occasions over 14 days (total 1,000 mg) 2
• Can be given as slow injection over 2-5 minutes or infusion over 15 minutes 2
• Alternative high-dose regimen: 500 mg infusion on Day 1 and Day 14 (total 1,000 mg), each infused over 3.5-4 hours 2

Peritoneal Dialysis Patients

• Three-dose regimen over 28 days: Two 300 mg infusions 14 days apart, followed by one 400 mg infusion 14 days later (total 1,000 mg) 2
• Each dose administered as infusion over 1.5-2.5 hours 2

Cancer-Related Anemia

• Total doses range: 937.5 mg to 2,000 mg depending on formulation and protocol 1
• Common regimens include:
  • 125-187.5 mg weekly for 5-8 weeks 1
  • 400 mg every 3 weeks for 5 doses (total 2,000 mg) 1
• Iron gluconate: 125 mg weekly for 8 weeks (total 1,000 mg) 1

Calculating Total Iron Dose

The total cumulative dose should be calculated based on formulas for body iron deficit, accounting for hemoglobin correction and iron store replenishment 1. The goal is to:

• Correct the hemoglobin deficit
• Rebuild iron stores to ferritin >200 ng/mL 1
• Achieve transferrin saturation >20% 1

Dosing Frequency and Interval

• Single doses should not exceed the maximum approved dose for the specific formulation 1
• Doses should be repeated every 3-7 days until total dose is administered 1
• For accurate monitoring, wait 2-7 days after the last dose before measuring iron indices (longer for higher doses) 1
• After a single dose ≥1,000 mg, wait 14 days before measuring transferrin saturation and ferritin 1

Monitoring and Safety Thresholds

Target Iron Parameters

• Ferritin target: >200 ng/mL for optimal erythropoiesis 1
• Transferrin saturation target: >20% 1
• Higher targets (ferritin 400 ng/mL, TSAT 30-50%) may reduce ESA requirements by 28% 1

Safety Limits

• Hold IV iron if ferritin exceeds 500 mg/L, especially in children and adolescents, to avoid iron overload toxicity 1
• Some guidelines suggest holding at ferritin >1,000 ng/mL or TSAT >50% 1
• Monitor iron status every 3 months during maintenance therapy 1

Special Populations

Pediatric Patients (≥2 years)

• Hemodialysis: 0.5 mg/kg (max 100 mg) every 2 weeks for 12 weeks 2
• Non-dialysis/peritoneal dialysis on ESA: 0.5 mg/kg (max 100 mg) every 4 weeks for 12 weeks 2
• Weight-based dosing for 10-dose course: 25-100 mg per dose depending on weight 1

Patients with Elevated Ferritin (500-1,200 ng/mL) but Low TSAT (<25%)

• Can still benefit from IV iron: 125 mg for 8 consecutive sessions showed significant hemoglobin increase (16 g/L vs 11 g/L in controls) 1
• Baseline ferritin was not predictive of iron responsiveness 1
• Exercise clinical judgment balancing potential benefit against theoretical iron overload risk 1

Common Pitfalls to Avoid

• Underdosing: Real-world data shows mean administered dose (1,244 mg) often falls short of estimated iron need (1,580 mg), leaving >65% of patients anemic 3
• Premature monitoring: Testing iron indices too soon after infusion yields inaccurate results 1
• Ignoring functional iron deficiency: Patients with "normal" ferritin (200-500 ng/mL) but low TSAT may still respond to IV iron 1
• Stopping at arbitrary ferritin levels: Consider continuing IV iron in select patients with ferritin 500-800 ng/mL if TSAT remains low and hemoglobin suboptimal 1

Expected Response

• Hemoglobin increase: Expect 14-20 g/L rise over 4-12 weeks 1, 3, 4
• Ferritin increase: Mean rise of 188-343 µg/L 1, 3, 4
• Response rate: 65-93% of patients achieve hemoglobin increase ≥20 g/L or become non-anemic 1, 3
• Time to response: Hemoglobin typically rises within 2-4 weeks, with continued improvement through 12 weeks 5, 4