Can We Start This Patient on Ferrous Sulfate?
No, ferrous sulfate (oral iron) should not be the primary treatment for anemia in ESRD patients—intravenous iron is strongly preferred and significantly more effective in this population. 1, 2
Why Oral Iron Is Inadequate in ESRD
Oral iron absorption is severely impaired in ESRD patients due to elevated hepcidin levels that block intestinal iron absorption through the hepcidin-ferroportin mechanism. 3
Oral iron achieves hemoglobin increases of only 4-7 g/L compared to 7-10 g/L with IV iron in CKD patients, making it substantially less effective. 3, 4
Poor patient compliance and gastrointestinal side effects (nausea, constipation, abdominal discomfort) frequently limit the effectiveness of oral iron supplementation in ESRD. 5, 2
Even when prescribed at the recommended dose of 200 mg elemental iron daily in divided doses, oral iron often fails to maintain adequate iron stores in dialysis patients receiving erythropoiesis-stimulating agents. 5, 6
The Superior Alternative: Intravenous Iron
IV iron bypasses the hepcidin-mediated intestinal absorption block, allowing direct delivery to bone marrow and achieving superior hemoglobin responses. 3, 1
IV iron is more effective than oral iron in adult CKD patients, particularly those on dialysis or approaching dialysis. 5, 1
KDIGO guidelines recommend a trial of IV iron when TSAT ≤30% and ferritin ≤500 ng/mL to increase hemoglobin without necessarily starting ESA therapy. 5
Approximately 59.4% of non-dialysis CKD patients respond to IV iron alone without requiring ESA therapy, demonstrating its effectiveness as monotherapy. 3, 4
When Oral Iron Might Be Considered (Rare Exceptions)
For non-dialysis CKD patients (stages 3-4) who refuse IV iron or lack venous access, a 1-3 month trial of oral iron may be attempted as an alternative, though it remains less effective. 5
The recommended oral iron dose is 200 mg elemental iron daily in 2-3 divided doses (e.g., ferrous sulfate 325 mg three times daily provides 195 mg elemental iron). 5
Oral iron should be taken without food or other medications to maximize absorption, though this further increases gastrointestinal side effects. 5
Critical Monitoring Parameters
Check TSAT and ferritin before initiating any iron therapy to establish baseline iron status and guide treatment selection. 5, 3
Monitor hemoglobin at least monthly in ESRD patients to assess treatment response. 5
Recheck iron parameters (TSAT and ferritin) at least every 3 months during ongoing treatment, but wait 4-8 weeks after IV iron before rechecking ferritin as it becomes falsely elevated immediately post-infusion. 5, 4
Safety Considerations for IV Iron
Within recommended guideline dosing, parenteral iron administration is safe and does not cause the inflammation or oxidative stress suggested by older animal studies. 1
Withhold IV iron during active infections (though not during chronic inflammation), as these patients were excluded from clinical trials. 5
Stop iron supplementation when ferritin exceeds 500-800 ng/mL or TSAT exceeds 50% to avoid iron overload complications. 4, 7
Personnel administering IV iron should be trained in emergency treatment with immediate access to medications for treating rare allergic reactions. 5
Common Pitfalls to Avoid
Never assume oral iron will be adequate in ESRD patients simply because it's cheaper or easier to prescribe—the poor efficacy means patients remain anemic longer, requiring higher ESA doses and potentially transfusions. 2, 6
Don't rely on ferritin alone to assess iron status in ESRD—ferritin acts as an acute-phase reactant and can be falsely elevated by inflammation, masking functional iron deficiency. 3
Avoid checking ferritin within 4 weeks of IV iron administration—results will be falsely elevated and misleading for clinical decision-making. 4