Iron Supplementation for Bariatric Patients
Start with oral ferrous sulfate 200 mg daily (or ferrous fumarate 210 mg or ferrous gluconate 300 mg), doubling the dose to twice daily for menstruating women, but be prepared to switch to intravenous iron if oral supplementation fails or after malabsorptive procedures like Roux-en-Y gastric bypass. 1, 2
Initial Oral Iron Strategy
Standard Dosing by Procedure Type
After sleeve gastrectomy or adjustable gastric banding: Begin with ferrous sulfate 200 mg once daily (65 mg elemental iron), ferrous fumarate 210 mg daily, or ferrous gluconate 300 mg daily 1, 2
For menstruating women after any bariatric procedure: Double the dose to twice daily administration to provide 100-140 mg elemental iron daily 1, 2
After Roux-en-Y gastric bypass or malabsorptive procedures (BPD/DS): Additional elemental iron beyond standard multivitamin supplementation is mandatory, as approximately 25% develop iron deficiency within 2 years 1, 2
Optimizing Oral Iron Absorption
Take iron with vitamin C: Administer with citrus fruits/drinks or 80-500 mg vitamin C to enhance absorption by forming an iron chelate 1, 2
Separate from calcium: Take calcium and iron supplements at least 2 hours apart, as calcium inhibits iron absorption 1, 2
Avoid proton pump inhibitors when possible: Reduced gastric acid secretion impairs iron absorption, which is already compromised after bariatric surgery 2
Timing matters: Take on an empty stomach for maximum absorption, though this may increase gastrointestinal side effects 2
When to Switch to Intravenous Iron
The American Gastroenterological Association recommends IV iron as the preferred treatment for iron deficiency after bariatric surgery, particularly in severe cases or when oral supplementation is ineffective. 2
Clear Indications for IV Iron
Severe iron deficiency anemia (hemoglobin below 10 g/dL) 2
Poor response to oral supplementation after 3 months of adequate dosing 2
After malabsorptive procedures like Roux-en-Y gastric bypass where duodenal and proximal jejunal absorption is bypassed 2
Intolerance to oral iron despite formulation changes or dose adjustments 2, 3
Anastomotic ulcers causing ongoing blood loss 2
IV Iron Options
Available formulations include low-molecular-weight iron dextran, iron sucrose, ferumoxytol, and ferric carboxymaltose, with selection based on cost considerations and potential side effects 2
Monitoring and Follow-Up
Check hemoglobin within 4 weeks of starting therapy; expect approximately 1 g/dL increase within 2 weeks if responding 2
Monitor iron studies regularly: Include serum ferritin, hemoglobin, and transferrin saturation 2
Continue treatment for 3 months after hemoglobin normalizes to ensure adequate repletion of marrow iron stores 2
Perform esophagogastroduodenoscopy in patients with post-surgical iron deficiency anemia to exclude anastomotic ulcers as a source of ongoing blood loss 2
Common Pitfalls to Avoid
Don't rely on multivitamins alone: Standard multivitamin and mineral supplements contain insufficient elemental iron to prevent deficiency after bariatric surgery 2
Don't ignore iron deficiency without anemia: Iron deficiency can significantly impair quality of life even before anemia develops 2
Don't forget gender differences: Women, particularly premenopausal women, are at significantly higher risk and require more aggressive supplementation 2
Don't overlook preoperative iron status: Patients with low iron stores before surgery are more likely to develop postoperative deficiency 2
Special Considerations by Procedure
Sleeve Gastrectomy
- Lower rates of iron deficiency compared to Roux-en-Y gastric bypass 2
- Long-term oral iron replacement is often effective 2
- Still requires additional iron beyond standard multivitamin 1
Roux-en-Y Gastric Bypass
- Highest risk for iron deficiency due to bypassed duodenum and proximal jejunum 2
- Approximately 25% develop iron deficiency within 2 years 2
- Lower threshold for switching to IV iron 2