When should intravenous (IV) iron be administered instead of oral (PO) iron?

From the Guidelines

Intravenous (IV) iron should be administered instead of oral (PO) iron in patients with severe iron deficiency anemia, malabsorption issues, or intolerance to oral preparations, as well as in those with inflammatory bowel disease, chronic kidney disease, heart failure, post-bariatric surgery, or during pregnancy when rapid correction is needed. This recommendation is based on the most recent and highest quality study available, which suggests that IV iron is more effective and better tolerated than oral iron in certain patient populations 1.

Patient Populations

The following patient populations may benefit from IV iron:

• Inflammatory bowel disease (IBD) patients with clinically active disease, previous intolerance to oral iron, or hemoglobin levels below 10 g/dL 1
• Patients with chronic kidney disease, especially those on hemodialysis 1
• Patients with heart failure or post-bariatric surgery 1
• Pregnant women in the 2nd and 3rd trimester who require rapid correction of iron deficiency anemia 1

IV Iron Preparations

Common IV iron preparations include:

• Iron sucrose (Venofer)
• Ferric carboxymaltose (Injectafer)
• Iron dextran (INFeD)
• Ferumoxytol (Feraheme) Dosing varies by preparation, with some requiring multiple administrations while others can be given as total dose infusions 1.

Benefits and Risks

IV iron provides faster hemoglobin improvement than oral iron, typically raising levels within 1-2 weeks versus 4-8 weeks with oral therapy 1. It bypasses the gastrointestinal tract, avoiding common oral iron side effects like constipation, nausea, and abdominal pain. However, IV administration carries risks of hypersensitivity reactions, so appropriate monitoring during infusion is essential 1.

Management of Infusion Reactions

Life-threatening infusion reactions are extremely rare, and concern for their occurrence should not be a barrier to the use of IV iron 1. For mild reactions, simply stopping the infusions and restarting 15 minutes later at a slower rate will suffice. For more severe reactions, corticosteroids may be of benefit 1.

From the FDA Drug Label

Intravenous or intramuscular injections of INFeD are indicated for treatment of patients with documented iron deficiency in whom oral administration is unsatisfactory or impossible. Intravenous (IV) iron should be administered instead of oral (PO) iron in patients with:

• Documented iron deficiency
• Unsatisfactory response to oral iron administration
• Impossible oral administration 2

From the Research

Indications for Intravenous Iron

Intravenous (IV) iron is indicated for the treatment of iron deficiency when oral preparations are ineffective or cannot be used 3, 4, 5. This includes clinical contexts such as:

• Chronic inflammatory conditions
• Perioperative settings
• Disorders associated with chronic blood loss
• Heart failure
• Chronic kidney disease
• Inflammatory bowel disease
• Patient blood management in the perioperative period
• Obstetrics and gynaecology

Conditions Where IV Iron is Preferred

IV iron may be preferred over oral iron in certain conditions, including:

• Intestinal malabsorption or prolonged inflammation 6
• Chronic kidney disease with inflammation, where IV iron therapy is superior to oral iron therapy 7
• Pregnancy, particularly in late pregnancy where oral iron may be inadequate for normal fetal brain development 5
• Heavy uterine bleeding or postpartum iron-deficiency anaemia 4

Administration Considerations

IV iron preparations can facilitate rapid iron repletion in one or two doses, and are generally well-tolerated with minimal risk of adverse events 3, 4, 5. However, potential side-effects should be anticipated and monitored, including:

• Headache
• Dizziness
• Nausea
• Abdominal pain
• Constipation
• Diarrhoea
• Rash
• Injection-site reactions

Treatment Strategy

The treatment strategy for iron deficiency anemia should be individualized, taking into account the presence of inflammation, the time available for iron replenishment, and the anticipated risk of side-effects or intolerance 3, 6, 7. IV iron therapy may be used if oral treatment lacks efficacy or causes side effects, or in the presence of intestinal malabsorption or prolonged inflammation 6.