What interventions are recommended for a 70-year-old female with iron deficiency anemia (IDA), mild chronic kidney disease (CKD), low ferritin, and impaired renal function, as indicated by an estimated glomerular filtration rate (eGFR) of 57?

Management of Iron Deficiency Anemia in a 70-Year-Old Female with Stage 3a CKD

This patient requires intravenous iron therapy as first-line treatment, not oral iron, due to the combination of severe iron deficiency anemia and chronic kidney disease. 1, 2

Immediate Diagnostic Priorities

Gastrointestinal evaluation is essential before initiating iron therapy. In a 70-year-old woman with severe iron deficiency (ferritin 14 ng/mL, iron saturation 5%), you must exclude GI malignancy as the source of chronic blood loss. 3 The British Society of Gastroenterology guidelines specifically emphasize that the majority of CKD patients with confirmed IDA warrant GI investigation as long as they are fit enough to undergo these procedures. 3

• Upper and lower GI tract evaluation should be performed, with consideration of CT colonography as an alternative to colonoscopy given her age. 3
• The prevalence of malignancy and dual unrelated pathology in this age group strengthens the case for imaging both upper and lower GI tract. 3
• This decision should ideally be made in conjunction with a nephrologist, weighing risks and benefits based on her overall fitness and comorbidities. 3

Iron Replacement Strategy

Initiate intravenous iron therapy immediately—oral iron is contraindicated in CKD patients due to poor absorption. 1, 2

IV Iron Dosing Protocol

• Administer 100-125 mg IV iron weekly for 8-10 doses (total 1,000 mg over 8-10 weeks) to rapidly replenish iron stores. 1, 2
• Alternative regimen: 500-1,000 mg iron dextran as a single IV infusion after a 25 mg test dose. 1
• Iron gluconate (250 mg twice monthly for 3 months) or iron sucrose are also effective alternative formulations. 1

Target Parameters

Aim for the following targets specific to CKD patients:

• Transferrin saturation >20% (ideally >30%) 1, 2
• Ferritin 100-500 ng/mL 1, 2
• Hemoglobin 11-12 g/dL 1, 2

Note that iron deficiency thresholds differ in CKD: absolute iron deficiency is defined as transferrin saturation ≤20% with ferritin ≤100 μg/L in predialysis patients (not the general population threshold of ferritin <12 ng/mL). 3, 4

Monitoring and Response Assessment

Check hemoglobin and iron parameters 2 weeks after completing the iron course. 1

• Expected response: Hemoglobin should increase by approximately 2 g/dL within 3-4 weeks of initiating IV iron therapy. 2
• Withhold IV iron if ferritin exceeds 500 ng/mL or transferrin saturation exceeds 30-50%. 1
• Once stable, monitor iron parameters and hemoglobin every 3 months. 1, 2
• Continue monitoring renal function (eGFR) given her CKD diagnosis. 1

Erythropoiesis-Stimulating Agents (ESAs)

Do not start ESAs initially—complete the trial of IV iron therapy first and reassess hemoglobin response. 1

• Only consider ESAs if hemoglobin fails to improve adequately after completing the IV iron course and achieving target iron parameters (ferritin >100 ng/mL, TSAT >20%). 1, 2
• Iron deficiency is the most common cause of hyporesponsiveness to ESAs, so optimizing iron stores first is critical. 4, 5

Maintenance Therapy

Once hemoglobin reaches 11-12 g/dL and ferritin is above 100 ng/mL, transition to maintenance IV iron at 25-125 mg monthly, adjusted based on iron parameters. 2

• Withhold IV iron if ferritin exceeds 800 ng/mL or transferrin saturation exceeds 50% to avoid iron overload. 2
• Recheck parameters in 3 months if iron is withheld. 2

Critical Pitfalls to Avoid

Common errors in managing this patient include:

• Never use oral iron in CKD patients—it is ineffective due to poor absorption and frequently causes GI side effects. 1, 2, 6
• Do not assume anemia is solely due to CKD—always investigate for reversible causes, particularly GI blood loss in elderly patients. 1
• Do not skip the GI evaluation—this is a 70-year-old with severe iron deficiency, making malignancy a significant concern. 3
• Do not start ESAs before optimizing iron stores—this leads to ESA hyporesponsiveness and increased costs. 1, 4
• Do not delay IV iron therapy in patients with severely low ferritin (14 ng/mL) and hemoglobin (9.3 g/dL). 2

Additional Considerations for CKD Stage 3a

With an eGFR of 57 mL/min/1.73m², this patient has Stage 3a CKD. While CKD becomes an increasingly likely cause of anemia when GFR <30 mL/min/1.73m², her severe iron deficiency (ferritin 14, TSAT 5%) is the dominant contributor to her anemia at this stage. 3

The causes of anemia in CKD are multifactorial, including reduced erythropoietin production, reduced iron absorption, and potential GI blood loss. 3 However, her iron parameters indicate absolute iron deficiency requiring aggressive repletion before considering other interventions. 4