Can a patient with Chronic Kidney Disease (CKD) take iron supplements?

Iron Supplementation in CKD: Recommended and Beneficial

Yes, patients with CKD can and should receive iron supplementation when indicated, with the route of administration (oral vs. intravenous) determined by CKD stage, iron parameters, and clinical context. 1

When to Initiate Iron Therapy

Iron supplementation should be started when specific laboratory thresholds are met:

• TSAT ≤30% AND ferritin ≤500 ng/mL if the goal is to increase hemoglobin without starting erythropoiesis-stimulating agents (ESAs) 1, 2
• For absolute iron deficiency: TSAT ≤20% and ferritin ≤100 ng/mL in non-dialysis and peritoneal dialysis patients, or ferritin ≤200 ng/mL in hemodialysis patients 3

The primary goals are avoiding blood transfusions, minimizing ESA requirements, and improving anemia-related symptoms. 1

Route Selection: Oral vs. Intravenous Iron

For Non-Dialysis CKD (Stages 3-5):

Intravenous iron is the preferred first-line choice when feasible, though a 1-3 month trial of oral iron is an acceptable alternative. 1, 2 This recommendation reflects that:

• IV iron produces significantly greater hemoglobin increases compared to oral iron in non-dialysis CKD patients 4, 5
• Oral iron absorption is impaired in CKD due to elevated hepcidin levels 4, 5
• Most CKD patients cannot maintain adequate iron stores with oral iron alone 2

For Hemodialysis Patients:

Intravenous iron is strongly preferred over oral iron, as these patients have:

• Severely impaired intestinal iron absorption 5
• Greater ongoing iron losses 5
• Higher iron requirements to support ESA-driven erythropoiesis 5

For Peritoneal Dialysis Patients:

Either IV or oral iron can be used, though IV iron demonstrates superior efficacy. 6

Oral Iron Regimens (When Selected)

If oral iron is chosen for non-dialysis CKD:

• 200 mg elemental iron daily, divided into 2-3 doses 2
• Take on an empty stomach without food or other medications for maximum absorption 2
• Avoid food within 2 hours before or 1 hour after dosing (reduces absorption by up to 50%) 2
• Separate from aluminum-based phosphate binders, which impair absorption 2

Preferred Oral Formulations:

Use ionic iron salts (ferrous sulfate, fumarate, or gluconate) as they are most cost-effective: 2

• Ferrous sulfate 325 mg = 65 mg elemental iron 2
• Ferrous fumarate 325 mg = 108 mg elemental iron 2
• Ferrous gluconate 325 mg = 35 mg elemental iron 2

Newer agents like ferric citrate (210 mg elemental iron per tablet, 3 times daily) and ferric maltol (30 mg twice daily) are also available. 1

Intravenous Iron Regimens

For Hemodialysis Patients:

• 100 mg IV iron per dialysis session to minimize dose-related arthralgias/myalgias 1
• Maintenance dosing: 250-1,000 mg within 12 weeks, administered thrice weekly, weekly, or every other week 1

For Non-Dialysis CKD:

• Two 500 mg infusions on Day 1 and Day 14 (iron sucrose over 3.5-4 hours), OR 6
• 200 mg over 2-5 minutes, 5 times within 14 days 6

For Peritoneal Dialysis:

• 300 mg on Days 1 and 15, then 400 mg on Day 29 6

Monitoring Strategy

Check iron parameters (TSAT and ferritin) and hemoglobin every 3 months once treatment is established. 2, 7

After a 1-3 month trial of oral iron, reassess:

• If inadequate response, switch to IV iron 2
• If ferritin >500 ng/mL or TSAT >50%, stop iron supplementation (unlikely to produce further hemoglobin increases) 2, 7

Critical Safety Considerations

Withhold IV iron during active infections, as these patients were excluded from clinical trials and iron is essential for microbial growth. 1

Avoid excessive iron administration:

• Stop when ferritin exceeds 500 ng/mL or TSAT exceeds 50% 7
• High-dose strategies more aggressive than those studied in major trials (PIVOTAL) require caution 1

Hypersensitivity reactions:

• True anaphylaxis is rare with modern IV iron preparations 8
• Iron dextran carries higher risk than dextran-free preparations (iron sucrose, ferric carboxymaltose) 4
• Limit single doses of iron dextran to ≤100 mg to minimize arthralgias/myalgias 1

Hypophosphatemia:

• More common with certain IV iron preparations (particularly ferric carboxymaltose) 8
• Clinical significance in CKD requires further study 8

Common Pitfalls to Avoid

• Don't rely on oral iron alone in hemodialysis patients—it is consistently inferior to IV iron 4, 5
• Don't measure iron parameters within 2-7 days of IV iron dosing (100-125 mg doses require 7 days; doses ≥1 gram require 14 days for accurate results) 1
• Don't continue escalating iron when ferritin and TSAT are adequate—this increases risk without benefit 7
• Don't assume normal ferritin excludes functional iron deficiency—check TSAT as well, as functional deficiency can exist with adequate stores 3

Managing Oral Iron Intolerance

If gastrointestinal side effects occur with oral iron: 2

• Try smaller, more frequent doses
• Start with lower doses and gradually increase
• Switch to a different iron salt preparation
• Take the supplement at bedtime