Details of I V iron treatment for Iron deficiency anemia.

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Intravenous iron for iron-deficiency anemia

IV iron replaces iron stores when oral iron is unsuitable, ineffective, poorly tolerated, or when rapid repletion is needed.

Common indications

Intolerance, poor adherence, malabsorption, or inadequate response to oral iron
Ongoing blood loss exceeding oral replacement capacity, such as heavy menstrual bleeding or gastrointestinal bleeding
Need for quicker correction, for example late pregnancy, preoperative anemia, or symptomatic severe anemia
Chronic kidney disease, especially in patients on erythropoiesis-stimulating agents or dialysis
Inflammatory bowel disease or other inflammatory states where oral absorption is impaired
Post-bariatric surgery iron deficiency

First establish iron deficiency where possible:

Low ferritin is strongly supportive, often <30 micrograms/L in otherwise healthy adults.
With inflammation, ferritin can be falsely elevated. Low transferrin saturation (TSAT), usually <20%, supports iron-restricted erythropoiesis.

Preparations and typical regimens

Preparation	Typical maximum single dose	Administration	Key points
Ferric carboxymaltose	Usually 750-1,000 mg	IV infusion over about 15 minutes or per product protocol	Convenient high-dose treatment. Can cause significant hypophosphatemia.
Ferric derisomaltose / iron isomaltoside	Up to 20 mg/kg, often maximum 1,000-1,500 mg depending on local labeling	Usually single infusion, often 20-60 minutes	Allows near-total replacement in one visit; monitor for hypersensitivity.
Iron sucrose	Usually 100-200 mg per infusion	Slow IV injection/infusion; repeated doses	Common in CKD and pregnancy. Often requires 5 or more visits for full replacement.
Sodium ferric gluconate	Usually 125 mg per dose	Infusion, repeated doses	Commonly used in hemodialysis protocols.
Ferumoxytol	Usually 510 mg, repeated after 3-8 days	IV infusion, per local protocol	Availability and indications vary by country. Can affect MRI interpretation for a period after administration.
Low-molecular-weight iron dextran	May be given as total-dose infusion	Slow infusion, protocol-specific	Less commonly used. Product-specific test-dose and monitoring policies may apply. High-molecular-weight dextran should not be used.

Use the exact licensed product information and institutional policy. Dose limits, dilution, infusion rate, and test-dose requirements differ by formulation and country.

Calculating the iron requirement

A practical approach in adults is to give 1,000 mg initially for most moderate iron-deficiency anemia, then reassess. Many adults with substantial anemia or ongoing loss need 1,500-2,000 mg total.

A traditional calculation is the Ganzoni formula:

[ \text{Total iron deficit (mg)} = \text{body weight (kg)} \times [\text{target Hb} - \text{actual Hb}],(\text{g/dL}) \times 2.4 + 500 ]

Use 500 mg for iron stores in most adults.
Target hemoglobin is often 13 g/dL, though local protocols vary.
Do not exceed the product's maximum permitted dose per infusion.

Example: 60-kg adult, Hb 8 g/dL, target Hb 13 g/dL:

[ 60 \times (13-8) \times 2.4 + 500 = 1,220 \text{ mg} ]

A reasonable regimen could be ferric carboxymaltose 1,000 mg, followed by 200-500 mg later if required, subject to product limits and reassessment.

Before giving IV iron

Confirm indication and cause of iron deficiency. Treatment should not replace investigation of important causes, particularly gastrointestinal blood loss in men and postmenopausal women.
Check:
- Full blood count with indices
- Ferritin and TSAT
- Renal function where relevant
- Serum phosphate if using ferric carboxymaltose in patients at risk or if repeated high doses are expected
Ask about:
- Previous reaction to IV iron
- Asthma, severe eczema, multiple drug allergies, or mastocytosis
- Active systemic infection
- Pregnancy trimester and obstetric context
Ensure staff, equipment, and medicines for managing anaphylaxis are immediately available.

Administration and observation

Give only in a monitored clinical setting with trained personnel.
Use the product-specific dilution and infusion rate.
Keep the patient under observation during infusion and for at least 30 minutes after completion, or longer if local policy requires.
Avoid unnecessary routine premedication with antihistamines. They can cause hypotension, tachycardia, and sedation that may confuse assessment of an infusion reaction.
Do not give IV iron during a prior unresolved serious hypersensitivity reaction to IV iron.

Adverse effects

Common, usually mild

Nausea, headache, dizziness
Flushing, metallic taste
Transient blood-pressure changes
Myalgia, arthralgia, feverish symptoms
Infusion-site discomfort

Infusion reactions

Minor reactions may include chest or back tightness, flushing, or itching without airway compromise or persistent hypotension. Stop the infusion, assess the patient, and manage according to the reaction severity and local protocol. Many mild reactions resolve and may allow cautious re-challenge at a slower rate after clinical review.

Severe hypersensitivity/anaphylaxis

Rare but potentially life-threatening:

Wheeze, stridor, airway swelling
Persistent hypotension, collapse
Generalized urticaria with systemic features

Stop infusion immediately and treat as anaphylaxis, with intramuscular adrenaline as first-line treatment according to emergency protocol.

Hypophosphatemia

This is especially associated with ferric carboxymaltose, particularly with repeated doses, low baseline phosphate, vitamin D deficiency, malnutrition, hyperparathyroidism, or inflammatory bowel disease.

Symptoms can include fatigue, weakness, bone pain, muscle pain, and in severe or prolonged cases, osteomalacia or fractures. Check phosphate in symptomatic people and in higher-risk patients receiving repeated courses. Consider an alternative IV iron formulation when recurrent or severe hypophosphatemia occurs.

Extravasation

Iron staining can be permanent. Use a secure IV cannula, check patency before and during infusion, and stop immediately if pain, swelling, or leakage occurs.

Expected response and follow-up

Reticulocytosis generally begins within about 1 week.
Hemoglobin commonly rises by approximately 1-2 g/dL over 2-4 weeks, provided the diagnosis is correct and blood loss is controlled.
Recheck hemoglobin around 2-4 weeks if clinically needed.
Reassess ferritin and TSAT no earlier than about 4-8 weeks after treatment, because values can be temporarily elevated soon after infusion.
Lack of response should prompt reassessment for ongoing bleeding, incorrect diagnosis, inflammation/anemia of chronic disease, B12 or folate deficiency, hemoglobinopathy, renal disease, or bone marrow pathology.

Important cautions

IV iron is not a substitute for red-cell transfusion in unstable patients, active major bleeding, or severe symptomatic anemia requiring immediate oxygen-carrying capacity.
Avoid use in confirmed iron overload.
Defer during uncontrolled active systemic infection unless the clinical need clearly outweighs the risk.
In pregnancy, IV iron is generally avoided in the first trimester unless there is a compelling reason. It is commonly used in the second and third trimesters when oral iron fails or rapid correction is necessary.
In CKD, targets and dosing should follow the renal service protocol because ferritin and TSAT interpretation differs with inflammation and erythropoiesis-stimulating therapy.

A practical adult outpatient plan is often: confirm iron deficiency and its cause, administer an appropriate high-dose formulation such as 1,000 mg if permitted, observe for reaction, then repeat CBC and iron studies after 4-8 weeks and provide additional iron only if the deficit remains or losses continue.

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