I have ferritin 26 ng/mL, serum iron 34 µg/dL, transferrin saturation approximately 10 % and am taking oral iron on a Monday‑Wednesday‑Friday schedule; what is the appropriate management?

Your Current Oral Iron Regimen Is Inadequate—Switch to Daily Dosing or Intravenous Iron

With a ferritin of 26 ng/mL, serum iron 34 µg/dL, and transferrin saturation of approximately 10%, you have confirmed absolute iron deficiency that requires immediate intensification of therapy; Monday-Wednesday-Friday dosing is insufficient and should be replaced with daily oral iron (100–200 mg elemental iron) or, preferably, intravenous iron if you have gastrointestinal intolerance, malabsorption, or fail to respond within 4–8 weeks. 1, 2, 3

---

Why Your Current Regimen Is Failing

• Transferrin saturation of 10% is well below the diagnostic threshold of 16–20%, confirming iron-deficient erythropoiesis—your bone marrow lacks sufficient available iron to produce hemoglobin. 1, 2
• Ferritin 26 ng/mL is below the 30 ng/mL cutoff that defines absolute iron deficiency in the absence of inflammation. 1, 2
• Monday-Wednesday-Friday dosing delivers only 3 doses per week, providing roughly 195 mg elemental iron weekly (assuming 65 mg per dose), which is inadequate to replenish depleted stores and correct ongoing deficiency. 3
• Daily dosing is required to deliver 100–200 mg elemental iron per day, totaling 700–1,400 mg weekly—substantially more than your current regimen. 1, 3

---

Immediate Next Steps: Optimize Oral Iron or Switch to IV

Step 1: Increase Oral Iron Frequency and Dose

• Switch to daily oral iron at 100–200 mg elemental iron per day (e.g., ferrous sulfate 325 mg once or twice daily, each tablet containing 65 mg elemental iron). 1, 3
• Take iron on an empty stomach (≥1 hour before or ≥2 hours after meals) to maximize absorption. 2
• Consider alternate-day dosing (every other day) if daily dosing causes gastrointestinal side effects; this approach improves fractional absorption by avoiding hepcidin-mediated blockade while still delivering more total iron than your current MWF schedule. 2

Step 2: Recognize When Oral Iron Will Fail

• If you have gastrointestinal intolerance (nausea, constipation, diarrhea), oral iron is unlikely to succeed and intravenous iron should be initiated. 1, 2, 3
• If you have chronic kidney disease (eGFR <30 mL/min/1.73 m²), heart failure, inflammatory bowel disease, or chronic infection, hepcidin-mediated blockade of intestinal iron absorption renders oral iron ineffective—intravenous iron is required. 1, 2
• If hemoglobin does not rise by ≥1–2 g/dL within 4–8 weeks of adequate daily oral iron, you are a non-responder and should switch to intravenous iron. 1, 2, 4

Step 3: Intravenous Iron Dosing

• For patients ≥50 kg, the recommended regimen is ferric carboxymaltose 750 mg intravenously on day 1 and day 8 (total 1,500 mg per course), or a single 1,000 mg dose. 5
• For patients <50 kg, administer 15 mg/kg body weight intravenously in two doses separated by at least 7 days. 5
• Do not recheck iron parameters within 4 weeks of IV iron infusion because circulating iron interferes with assays and ferritin will be falsely elevated; reassess at 4–8 weeks. 1, 2

---

Treatment Targets After Iron Repletion

• Ferritin ≥30 ng/mL (in the absence of inflammation) or ≥100 ng/mL (if chronic inflammatory conditions are present). 1, 2
• Transferrin saturation ≥20% to ensure adequate iron availability for erythropoiesis. 1, 2
• Hemoglobin rise of 1–2 g/dL within 4–8 weeks confirms therapeutic response. 1, 4

---

Mandatory Investigation for Underlying Cause

• In men and postmenopausal women, gastrointestinal evaluation (bidirectional endoscopy) is mandatory to exclude malignancy as a source of chronic blood loss. 6, 3
• In premenopausal women, assess menstrual blood loss patterns to identify gynecologic sources of iron loss. 2, 3
• Screen for celiac disease with serologic testing, as 2–5% of iron-deficiency anemia cases are due to celiac disease. 6, 3
• Document NSAID/aspirin use and discontinue if possible, as these are common causes of occult gastrointestinal bleeding. 6, 3
• Evaluate dietary iron intake, particularly in vegetarians or those with restrictive eating patterns. 3

---

Common Pitfalls to Avoid

• Do not assume dietary deficiency alone without excluding pathologic causes, especially in men and postmenopausal women—gastrointestinal malignancy must be ruled out. 3
• Do not delay investigation pending response to iron therapy in men or postmenopausal women, as this may miss gastrointestinal malignancy. 3
• Do not rely on serum iron alone to assess iron status; serum iron exhibits high day-to-day variability, diurnal fluctuations, and is affected by recent meals and inflammation—ferritin and transferrin saturation are far more reliable. 1, 2, 3
• Do not continue oral iron indefinitely if there is no hematologic response after 4–8 weeks; this indicates malabsorption, ongoing blood loss, or hepcidin-mediated blockade requiring intravenous iron. 1, 2
• Do not measure iron parameters within 4 weeks of IV iron infusion; circulating iron produces falsely elevated results. 1, 2

---

Why Alternate-Day Dosing May Be Superior to MWF

• Alternate-day dosing (every other day) delivers 3.5 doses per week (e.g., Monday, Wednesday, Friday, Sunday, Tuesday, Thursday, Saturday…), providing more total iron than your current MWF schedule while avoiding hepcidin-mediated blockade that occurs with daily dosing. 2
• Daily oral iron sustains elevated hepcidin for up to 24 hours, markedly reducing subsequent iron uptake; alternate-day dosing allows hepcidin to fall between doses, improving fractional absorption. 2
• If you tolerate daily dosing without gastrointestinal side effects, daily administration is preferred because it delivers the highest total weekly iron dose (700–1,400 mg elemental iron per week). 1, 3

---

Summary Algorithm

1. Confirm absolute iron deficiency: Ferritin 26 ng/mL + TSAT 10% = absolute iron deficiency. 1, 2
2. Increase oral iron to daily dosing (100–200 mg elemental iron per day) or alternate-day dosing if gastrointestinal side effects occur. 1, 2, 3
3. Switch to intravenous iron if:
   • Gastrointestinal intolerance to oral iron,
   • Chronic kidney disease (eGFR <30 mL/min/1.73 m²),
   • Heart failure, inflammatory bowel disease, or chronic infection,
   • No hemoglobin rise of ≥1–2 g/dL within 4–8 weeks of adequate oral therapy. 1, 2, 3, 5
4. Investigate underlying cause: Gastrointestinal evaluation (men and postmenopausal women), menstrual history (premenopausal women), celiac screening, NSAID use, dietary assessment. 6, 3
5. Reassess iron parameters at 4–8 weeks (not sooner if IV iron was given) and target ferritin ≥30–100 ng/mL + TSAT ≥20%. 1, 2