What are the guidelines for administering iron infusions?

Iron Infusion Guidelines

Formulation Selection

Single total-dose infusion (TDI) formulations are strongly recommended over multiple-dose regimens to minimize healthcare visits and improve patient compliance. 1

Optimal TDI Formulations (in order of preference):

• Ferric derisomaltose (FDI): Up to 20 mg/kg in a single administration with significantly lower hypophosphatemia rates (4%) compared to ferric carboxymaltose (58%) 2
• Low molecular weight iron dextran (LMWID): 1000 mg in 250 mL normal saline over 1 hour after a 25 mg test dose or slow 5-minute initiation 1, 2
• Ferumoxytol: 1020 mg over 30 minutes as TDI 1

Suboptimal Formulations (require multiple visits):

• Ferric carboxymaltose (FCM): Maximum 750 mg per dose, requires two doses separated by at least 7 days for complete repletion 1, 3
• Iron sucrose: Maximum safe dose 200-300 mg per administration over 1-2 hours; requires 4-7 visits for complete iron repletion 1, 4, 5
• Ferric gluconate: Maximum 125 mg per dose, requires multiple administrations 6

Pre-Administration Assessment

Patient Risk Stratification:

• No test dose required for iron sucrose, ferric carboxymaltose, or ferumoxytol 1, 4
• Test dose required for low molecular weight iron dextran (25 mg) 2
• Evaluate for active infection (contraindication to IV iron) 4
• Assess pregnancy status: avoid IV iron before 13 weeks gestation 1

Laboratory Requirements:

• Baseline hemoglobin, ferritin, and transferrin saturation 2
• Goal ferritin is 50 ng/mL regardless of sex 1, 2

Administration Protocols

Ferric Carboxymaltose (FCM):

• ≥50 kg patients: 750 mg IV in two doses separated by at least 7 days (total 1500 mg per course) 3
• <50 kg patients: 15 mg/kg body weight IV in two doses separated by at least 7 days 3
• Alternative: 15 mg/kg up to maximum 1000 mg as single dose 3
• Dilute up to 1000 mg in no more than 250 mL 0.9% sodium chloride (minimum concentration 2 mg/mL) 3
• Infuse over at least 15 minutes, or give undiluted as slow IV push at 100 mg/min 3

Iron Sucrose:

• Standard dose: 200 mg IV push over 10 minutes without dilution 4, 7
• Maximum safe dose: 300 mg diluted in 100 mL normal saline over 1-2 hours 5
• Do not exceed 300 mg per dose - doses of 400-500 mg cause unacceptable reaction rates 2, 5
• For hemodialysis patients: 100 mg directly into dialysis line 2-3 times weekly 4

Ferric Gluconate:

• Adult dose: 125 mg diluted in 100 mL 0.9% sodium chloride over 1 hour per dialysis session 6
• Alternative: undiluted slow IV injection at maximum rate of 12.5 mg/min 6
• Pediatric dose (≥6 years): 1.5 mg/kg diluted in 25 mL 0.9% sodium chloride over 1 hour 6

Safety Monitoring

During Administration:

• Monitor for hypersensitivity reactions for at least 30 minutes after completion and until clinically stable 1, 3, 6
• Resuscitation equipment and trained personnel must be immediately available 1, 3, 6
• Post-infusion monitoring for 30 minutes is not routinely indicated for low-risk patients 1
• Monitor for extravasation (can cause long-lasting brown discoloration) 3

Premedication:

• Reserve premedication only for patients at high risk of hypersensitivity reactions 1
• Allow 30 minutes between IV iron and other medications in high-risk patients 1
• No fetal monitoring required during or after IV iron administration in pregnancy 1

Post-Administration Management

Laboratory Monitoring:

• Recheck CBC and iron parameters 4-8 weeks after infusion 2
• Hemoglobin should increase within 1-2 weeks and rise by 1-2 g/dL within 4-8 weeks 2
• For repeat courses within 3 months, check serum phosphate levels due to hypophosphatemia risk 3
• Maintain ferritin <500 μg/L to avoid iron overload toxicity 4

Hypophosphatemia Monitoring:

• Ferric carboxymaltose carries highest risk (up to 58% incidence) 2
• Symptomatic hypophosphatemia can cause osteomalacia and fractures requiring clinical intervention 3
• Monitor phosphate levels in all patients receiving repeat courses, especially with FCM 3

Infusion Reaction Management

Reaction Classification:

• Anaphylaxis is exceedingly rare (<1:200,000 administrations) 1, 4
• Most reactions are complement-activated related pseudo-allergy (CARPA/Fishbane reactions), not true anaphylaxis 1
• Common mild reactions include metallic taste (17.9% with iron sucrose), transient hypotension, nausea 7

Management Strategy:

• Rechallenge with the same formulation may be attempted following an infusion reaction 1
• For mild reactions (metallic taste, flushing): slow infusion rate 8
• For hypotension: administer 500 mL normal saline 8
• Serious reactions require standard anaphylaxis management protocols 1

Critical Pitfalls to Avoid

• Never administer iron dextran >1000 mg or iron gluconate >125 mg as rapid bolus - dramatically increases reaction risk 2
• Never dilute ferric carboxymaltose to <2 mg iron/mL - causes instability 3
• Avoid iron sucrose and ferric gluconate in outpatient settings requiring complete repletion - these formulations bind iron less tightly and require 4-7 visits 2
• Do not mix IV iron with other medications or add to parenteral nutrition 6
• Do not administer to patients with active infection 4