What is the urgent management for a patient who had an allergic reaction to intravenous iron infusion and now has elevated red cell distribution width (RDW), elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST), leukocytosis, neutrophilia, lymphocytosis, increased anion gap, high serum iron, high total iron‑binding capacity (TIBC), low unsaturated iron‑binding capacity (UIBC), and increased total protein?

Urgent Management of Post-Iron Infusion Allergic Reaction with Laboratory Abnormalities

Stop any ongoing iron administration immediately, maintain IV access with normal saline at keep-vein-open rate, and focus on managing the acute allergic reaction rather than the laboratory abnormalities, which likely reflect the acute inflammatory response and iron redistribution rather than requiring specific urgent intervention. 1

Immediate Acute Reaction Management

Stop Infusion and Stabilize Access

• Immediately cease any ongoing iron infusion and switch IV line to normal saline at KVO rate to maintain venous access 1, 2
• Monitor vital signs continuously: blood pressure, pulse, respiratory rate, oxygen saturation, and temperature 2
• Perform rapid physical assessment to classify reaction severity (mild, moderate, or severe/life-threatening) 1

Severity-Based Treatment Protocol

For Mild to Moderate Reactions (most common scenario):

• Stop infusion and monitor for 15 minutes with IV saline running 1
• Most reactions are self-limiting and will resolve spontaneously 1
• If symptoms persist or worsen after 15 minutes, administer hydrocortisone 200 mg IV (or equivalent corticosteroid) 1
• For specific symptoms:
  • Nausea: 5-HT3 antagonist (ondansetron 4-8 mg IV) 1, 2
  • Urticaria: Second-generation antihistamine (loratadine 10 mg orally OR cetirizine 10 mg IV/oral) 1, 2
  • Mild hypotension: IV hydration with normal saline bolus 1000-2000 mL 2
  • Hypoxemia: Oxygen by mask or nasal cannula 2

Critical Caveat - Avoid These Medications:

• Do NOT administer first-generation antihistamines (diphenhydramine) or vasopressors, as these can convert minor reactions into hemodynamically significant serious adverse events including exacerbation of hypotension, tachycardia, diaphoresis, sedation, and shock 1, 2
• Second-generation antihistamines are safer but can still cause flushing, palpitations, and dizziness 1

For Severe/Life-Threatening Reactions (rare but critical):

• If sudden onset with rapid symptom intensification, loss of consciousness, severe hypotension, angioedema of tongue/airway, or multi-organ involvement occurs, this constitutes a true medical emergency 1, 2
• Immediately call emergency services and administer EPINEPHRINE 0.3 mg IM (1 mg/mL concentration) into anterolateral mid-third of thigh 2
• Consider β2 agonist nebulizer (Albuterol 0.083%) for respiratory symptoms 2
• Manage as anaphylaxis from any cause 1

Understanding the Laboratory Abnormalities

These Lab Changes Do Not Require Urgent Specific Treatment

The laboratory abnormalities you describe (elevated RDW, transaminases, WBC, neutrophils, anion gap, serum iron, TIBC; low UIBC, total protein, lymphocytes) represent:

1. Acute inflammatory response to the allergic reaction (elevated WBC, neutrophils, transaminases) 3, 4
2. Iron redistribution following infusion (high serum iron, altered TIBC/UIBC) - this is expected after IV iron administration
3. Possible complement activation-related pseudo-allergy (CARPA), the most common mechanism for IV iron reactions with current formulations, rather than true IgE-mediated anaphylaxis 4, 5, 6

These laboratory values should be monitored but do not drive acute management decisions - focus remains on clinical assessment and symptom-directed treatment of the allergic reaction itself.

Post-Stabilization Monitoring and Documentation

Observation Period

• Monitor until complete resolution of symptoms - there is no physiological basis for the standard 30-minute post-infusion observation period since IV iron is not associated with severe delayed reactions 1
• However, given this patient had an acute reaction, extended observation until symptom resolution is warranted 1

Patient Education on Delayed Reactions

• Inform patient that delayed infusion reactions can occur hours to days after infusion 1
• Most common delayed symptoms include flu-like symptoms, arthralgias, myalgias, and fever lasting up to 24 hours 1
• These are easily managed with NSAIDs 1, 2
• Symptoms lasting more than a few days require provider evaluation and may indicate other pathologies such as treatment-emergent hypophosphatemia (occurs within first 2 weeks with certain formulations) 1

Critical Documentation

• Document the specific reaction symptoms, timing, severity classification, and management interventions in medical record 7, 2
• This documentation is essential for future iron administration decisions 7

Future Iron Administration Considerations

Do NOT Automatically Avoid IV Iron

• Avoidance of IV iron products in patients with hypersensitivity reactions should not be considered standard practice 3
• Rechallenge may be appropriate depending on reaction severity and clinical need 1

If Future IV Iron Required:

• Consider alternative iron formulation (different carbohydrate core may have different reactivity profile) 1, 7, 2
• Use slower infusion rates - faster rates are associated with higher reaction risk 7, 2, 4, 6
• Premedication remains controversial and should be limited to patients with substantial risk factors (multiple drug allergies, prior IV iron reaction, severe asthma/atopy) 1, 3, 4
• Ensure administration only by staff trained in managing anaphylactic/anaphylactoid reactions with resuscitation facilities immediately available 1

Contraindications for Future IV Iron:

• Active infection (do not give IV iron) 1
• Concomitant cardiotoxic chemotherapy (give iron before, after, or at end of treatment cycle) 1
• Early pregnancy 4

Key Pathophysiology Note

The reaction mechanism is most likely complement activation-related pseudo-allergy (CARPA) rather than true IgE-mediated anaphylaxis - this distinction matters because true anaphylaxis to IV iron is exceedingly rare (<1:200,000 to 1:250,000 administrations) 1, 4, 5, 6. CARPA reactions are triggered by iron nanoparticles and respond differently to treatment, which is why aggressive use of antihistamines and vasopressors can worsen outcomes 1, 5.