Management of Iron Deficiency Anemia in Older Adults

Diagnostic Confirmation

Ferritin < 45 ng/mL confirms absolute iron deficiency; a level of 19 ng/mL is diagnostic in this patient population. 3
Transferrin saturation < 20% indicates iron deficiency; a value of 10% confirms true deficiency rather than functional anemia of inflammation. 4

Oral ferrous sulfate 325 mg (≈105 mg elemental iron) once daily is recommended as the standard initial regimen for iron‑deficiency anemia. 1
The optimal elemental iron dose is 50–100 mg daily, balancing efficacy with tolerability. 1
Iron should be taken on an empty stomach for maximal absorption; if gastrointestinal upset occurs, it may be taken with meals, acknowledging a modest reduction in absorption. 2
Once‑daily dosing is sufficient because hepcidin remains elevated for ~48 h after an iron dose, limiting additional absorption from more frequent dosing. 2
Alternate‑day dosing can improve tolerability while providing comparable overall efficacy, although further research is needed to confirm equivalence. [1][2]
Co‑administration of vitamin C ≈ 500 mg enhances iron absorption even in the presence of calcium or fiber. 2
Consuming iron with meat protein further augments absorption. 2

Hemoglobin should be reassessed after 2 weeks of oral therapy. 1
An increase of ≥10 g/L in hemoglobin at 2 weeks is the expected response to daily oral iron. 1
Failure to achieve a ≥10 g/L rise predicts subsequent treatment failure with 90.1 % sensitivity and 79.3 % specificity. 1

Intolerance to oral iron (nausea ≈ 12 %, constipation ≈ 12 %, abdominal pain ≈ 11 %) warrants transition to IV iron. 2
Inadequate hemoglobin response after 2–4 weeks despite confirmed adherence indicates the need for IV therapy. 1
Presence of chronic inflammatory conditions may justify IV iron, especially when oral absorption is compromised. 2

All men and post‑menopausal women with iron deficiency should undergo bidirectional gastrointestinal endoscopy to identify occult bleeding sources. 3
Non‑invasive testing for Helicobacter pylori is recommended as it is a common reversible cause of iron loss. 2
Screening for celiac disease with tissue transglutaminase antibody testing should be performed given its association with malabsorption‑related iron deficiency. 2

Prescribing iron more than once daily increases adverse effects without improving absorption due to hepcidin‑mediated blockade. 2
Modified‑release iron formulations are not recommended because they provide inferior absorption profiles. 1
Switching between different oral iron salts (e.g., ferrous sulfate to ferrous gluconate) lacks supporting evidence; instead, consider alternate‑day dosing or IV iron if side effects persist. 1